Year 4: Using known facts, word problems and the times table check
Part of the Year 4 times tables chapter. Chapter overview · whole chapter on one page · Download worksheet (PDF) · Answers (PDF)
Using known facts, word problems and the times table check
Use a fact you know to work out new facts. Suppose you know 6 × 7 = 42. Then 60 is 6 tens, so 60 × 7 is 6 tens × 7 = 42 tens = 420. In the same way, 6 × 70 = 420 (6 groups of 7 tens) and 600 × 7 = 4,200 (42 hundreds). The digits stay the same and the zeros move along. Division works the same way: 420 ÷ 7 = 60 and 4,200 ÷ 7 = 600.
You can also get a new fact from a nearby fact. Add or take away one group: 7 × 7 is 6 × 7 plus one more 7, which is 42 + 7 = 49. Double: 12 × 7 is double 6 × 7, so double 42 is 84. Halve: 3 × 7 is half of 6 × 7, so half of 42 is 21.
Word problems. Read the problem twice. Draw a bar model. If you know the size of each group and the number of groups, multiply to find the total. If you know the total and want to share it equally, or find how many groups, divide. Write the unit (like £, cm or “pens”) in your answer.
The times tables check. In Year 4 you take a short check on the computer. There are 25 questions like 7 × 8 = ?, and you get 6 seconds for each one. The best preparation is a little practice every day. Make sure you know the ten tricky facts where both numbers are from 6 to 9 (shaded below), and use the tricks in this chapter to build any fact in a flash. The practice sets in this section use the same style: 25 questions, 6 seconds each. Cover the answers and see how many you can do in time!
Key words. A known fact is a fact you can recall. A derived fact is a new fact that you work out from a known fact.
Key ideas
- Use a known fact and place value: 6 × 7 = 42, so 60 × 7 = 420, 6 × 70 = 420 and 600 × 7 = 4,200.
- Division too: 42 ÷ 7 = 6, so 420 ÷ 7 = 60.
- Nearby facts: add or take away one group. Double or halve the number of groups.
- Equal groups with a total to find: multiply. A total to share or split into groups: divide.
- Times tables check: 25 questions, 6 seconds each.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 6 × 7 = 42, and place value. 60 is 6 tens, so the answer is 42 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.6 × 7 = 42
- Say the bigger number in tens. 60 is 6 tens.60 = 6 tens
- Multiply, using the known fact. 6 tens × 7 = 42 tens, because 6 × 7 = 42.6 × 7 = 42, so 6 tens × 7 = 42 tens
- Change 42 tens back to a number. 1 ten is 10, so 42 tens is 42 × 10. 42 tens = 420
- Write the answer. 60 × 7 = 420
Check. Divide back: 420 ÷ 7 = 60. ✓
Watch out. The answer is 42 tens, which has 1 zero on the end. Count the zeros carefully.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 4 × 8 = 32, and place value. 80 is 8 tens, so the answer is 32 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.4 × 8 = 32
- Say the bigger number in tens. 80 is 8 tens.80 = 8 tens
- Multiply, using the known fact. 8 tens × 4 = 32 tens, because 8 × 4 = 32.8 × 4 = 32, so 8 tens × 4 = 32 tens
- Change 32 tens back to a number. 1 ten is 10, so 32 tens is 32 × 10. 32 tens = 320
- Write the answer. 4 × 80 = 320
Check. Divide back: 320 ÷ 80 = 4. ✓
Watch out. The answer is 32 tens, which has 1 zero on the end. Count the zeros carefully.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 9 × 5 = 45, and place value. 900 is 9 hundreds, so the answer is 45 hundreds.
- Spot the fact you know. Take away the zeros and look at the digits that are left.9 × 5 = 45
- Say the bigger number in hundreds. 900 is 9 hundreds.900 = 9 hundreds
- Multiply, using the known fact. 9 hundreds × 5 = 45 hundreds, because 9 × 5 = 45.9 × 5 = 45, so 9 hundreds × 5 = 45 hundreds
- Change 45 hundreds back to a number. 1 hundred is 100, so 45 hundreds is 45 × 100. 45 hundreds = 4,500
- Write the answer. 900 × 5 = 4,500
Check. Divide back: 4,500 ÷ 5 = 900. ✓
Watch out. The answer is 45 hundreds, which has 2 zeros on the end. Count the zeros carefully.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 56 ÷ 8 = 7, and place value. 560 is 56 tens, so the answer is 7 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.56 ÷ 8 = 7
- Say the big number in tens. 560 is 56 tens.560 = 56 tens
- Divide, using the known fact. 56 tens ÷ 8 = 7 tens, because 56 ÷ 8 = 7.56 ÷ 8 = 7, so 56 tens ÷ 8 = 7 tens
- Change 7 tens back to a number. Put the zeros back.7 tens = 70
- Write the answer. 560 ÷ 8 = 70
Check. Multiply back: 70 × 8 = 560. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 36 ÷ 9 = 4, and place value. 3,600 is 36 hundreds, so the answer is 4 hundreds.
- Spot the fact you know. Take away the zeros and look at the digits that are left.36 ÷ 9 = 4
- Say the big number in hundreds. 3,600 is 36 hundreds.3,600 = 36 hundreds
- Divide, using the known fact. 36 hundreds ÷ 9 = 4 hundreds, because 36 ÷ 9 = 4.36 ÷ 9 = 4, so 36 hundreds ÷ 9 = 4 hundreds
- Change 4 hundreds back to a number. Put the zeros back.4 hundreds = 400
- Write the answer. 3,600 ÷ 9 = 400
Check. Multiply back: 400 × 9 = 3,600. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A derived fact is a new fact you work out from a fact you already know.
Method. 7 is one more than 6, so add one more group of 8 to the answer to 6 × 8.
- Write the fact you know. We start from the fact we know.6 × 8 = 48
- Compare 7 with 6. 7 is one more than 6, so we need one more group of 8.7 = 6 + 1
- Add one more group. One group is 8.48 + 8 = 56
- Write the answer. 7 × 8 = 56
Check. Check by dividing: 56 ÷ 8 = 7. ✓
Watch out. Add 8, the size of one group, not 7 or 1.
Key words. A derived fact is a new fact you work out from a fact you already know.
Method. 12 is double 6, so double the answer to 6 × 7.
- Write the fact you know. We start from the fact we know.6 × 7 = 42
- Compare 12 with 6. 12 is double 6, so 12 groups of 7 are double 6 groups of 7.12 = 2 × 6
- Double the known answer. double 40 = 80, double 2 = 4, so 80 + 4 = 84
- Write the answer. 12 × 7 = 84
Check. Check by dividing: 84 ÷ 7 = 12. ✓
Watch out. Doubling the number of groups doubles the total. Do not double the other number as well.
Method. Two steps. First find how many pencils Leo buys by multiplying. Then take away the pencils he gives away.
- Draw a bar model for step 1. 6 equal packs of 12. We want the total.
- Step 1: multiply. Equal groups, so multiply.10 × 6 = 60
6 + 6 = 12
60 + 12 = 72
6 × 12 = 72 - Step 2: take away. Leo gives 15 pencils away. Take 10 first, then 5.72 − 10 = 62, then 62 − 5 = 57
- Write the answer. 57 pencils
Check. Add back: 57 + 15 = 72 and 72 ÷ 6 = 12. ✓
Watch out. The answer to step 1 (72) is not the final answer. Check what the question asks for.
Method. Dividing is the opposite of multiplying. Use the times table to find how many times the number fits.
- Draw a bar model. The whole is 72. It is split into 8 equal parts. We want the size of one part.
- Choose the operation. Sharing equally means dividing.72 ÷ 8
- Use the times tables. Think: what do we multiply 8 by to get 72?9 × 8 = 72, so 72 ÷ 8 = 9
- Write the answer. Include the unit.9 apples
Check. Multiply back: 9 × 8 = 72. ✓
Watch out. Read the question carefully. Does it ask for the size of each group, or for how many groups?
Watch out
Keep the zeros! 60 × 7 is 420, not 42. Write the known fact first, then say how many tens or hundreds you have. In word problems, do not choose multiply or divide because of one word in the question. Draw a bar model and decide if you know the total or the size of each group.Exercise 3G Using known facts
Non-calculatorKey words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 6 × 4 = 24, and place value. 60 is 6 tens, so the answer is 24 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.6 × 4 = 24
- Say the bigger number in tens. 60 is 6 tens.60 = 6 tens
- Multiply, using the known fact. 6 tens × 4 = 24 tens, because 6 × 4 = 24.6 × 4 = 24, so 6 tens × 4 = 24 tens
- Change 24 tens back to a number. 1 ten is 10, so 24 tens is 24 × 10. 24 tens = 240
- Write the answer. 60 × 4 = 240
Check. Divide back: 240 ÷ 4 = 60. ✓
Watch out. The answer is 24 tens, which has 1 zero on the end. Count the zeros carefully.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 6 × 4 = 24, and place value. 40 is 4 tens, so the answer is 24 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.6 × 4 = 24
- Say the bigger number in tens. 40 is 4 tens.40 = 4 tens
- Multiply, using the known fact. 4 tens × 6 = 24 tens, because 4 × 6 = 24.4 × 6 = 24, so 4 tens × 6 = 24 tens
- Change 24 tens back to a number. 1 ten is 10, so 24 tens is 24 × 10. 24 tens = 240
- Write the answer. 6 × 40 = 240
Check. Divide back: 240 ÷ 40 = 6. ✓
Watch out. The answer is 24 tens, which has 1 zero on the end. Count the zeros carefully.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 6 × 4 = 24, and place value. 600 is 6 hundreds, so the answer is 24 hundreds.
- Spot the fact you know. Take away the zeros and look at the digits that are left.6 × 4 = 24
- Say the bigger number in hundreds. 600 is 6 hundreds.600 = 6 hundreds
- Multiply, using the known fact. 6 hundreds × 4 = 24 hundreds, because 6 × 4 = 24.6 × 4 = 24, so 6 hundreds × 4 = 24 hundreds
- Change 24 hundreds back to a number. 1 hundred is 100, so 24 hundreds is 24 × 100. 24 hundreds = 2,400
- Write the answer. 600 × 4 = 2,400
Check. Divide back: 2,400 ÷ 4 = 600. ✓
Watch out. The answer is 24 hundreds, which has 2 zeros on the end. Count the zeros carefully.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 24 ÷ 4 = 6, and place value. 240 is 24 tens, so the answer is 6 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.24 ÷ 4 = 6
- Say the big number in tens. 240 is 24 tens.240 = 24 tens
- Divide, using the known fact. 24 tens ÷ 4 = 6 tens, because 24 ÷ 4 = 6.24 ÷ 4 = 6, so 24 tens ÷ 4 = 6 tens
- Change 6 tens back to a number. Put the zeros back.6 tens = 60
- Write the answer. 240 ÷ 4 = 60
Check. Multiply back: 60 × 4 = 240. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 24 ÷ 4 = 6, and place value. 2,400 is 24 hundreds, so the answer is 6 hundreds.
- Spot the fact you know. Take away the zeros and look at the digits that are left.24 ÷ 4 = 6
- Say the big number in hundreds. 2,400 is 24 hundreds.2,400 = 24 hundreds
- Divide, using the known fact. 24 hundreds ÷ 4 = 6 hundreds, because 24 ÷ 4 = 6.24 ÷ 4 = 6, so 24 hundreds ÷ 4 = 6 hundreds
- Change 6 hundreds back to a number. Put the zeros back.6 hundreds = 600
- Write the answer. 2,400 ÷ 4 = 600
Check. Multiply back: 600 × 4 = 2,400. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 24 ÷ 6 = 4, and place value. 240 is 24 tens, so the answer is 4 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.24 ÷ 6 = 4
- Say the big number in tens. 240 is 24 tens.240 = 24 tens
- Divide, using the known fact. 24 tens ÷ 6 = 4 tens, because 24 ÷ 6 = 4.24 ÷ 6 = 4, so 24 tens ÷ 6 = 4 tens
- Change 4 tens back to a number. Put the zeros back.4 tens = 40
- Write the answer. 240 ÷ 6 = 40
Check. Multiply back: 40 × 6 = 240. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 8 × 7 = 56, and place value. 80 is 8 tens, so the answer is 56 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.8 × 7 = 56
- Say the bigger number in tens. 80 is 8 tens.80 = 8 tens
- Multiply, using the known fact. 8 tens × 7 = 56 tens, because 8 × 7 = 56.8 × 7 = 56, so 8 tens × 7 = 56 tens
- Change 56 tens back to a number. 1 ten is 10, so 56 tens is 56 × 10. 56 tens = 560
- Write the answer. 80 × 7 = 560
Check. Divide back: 560 ÷ 7 = 80. ✓
Watch out. The answer is 56 tens, which has 1 zero on the end. Count the zeros carefully.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 8 × 7 = 56, and place value. 70 is 7 tens, so the answer is 56 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.8 × 7 = 56
- Say the bigger number in tens. 70 is 7 tens.70 = 7 tens
- Multiply, using the known fact. 7 tens × 8 = 56 tens, because 7 × 8 = 56.7 × 8 = 56, so 7 tens × 8 = 56 tens
- Change 56 tens back to a number. 1 ten is 10, so 56 tens is 56 × 10. 56 tens = 560
- Write the answer. 8 × 70 = 560
Check. Divide back: 560 ÷ 70 = 8. ✓
Watch out. The answer is 56 tens, which has 1 zero on the end. Count the zeros carefully.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 8 × 7 = 56, and place value. 800 is 8 hundreds, so the answer is 56 hundreds.
- Spot the fact you know. Take away the zeros and look at the digits that are left.8 × 7 = 56
- Say the bigger number in hundreds. 800 is 8 hundreds.800 = 8 hundreds
- Multiply, using the known fact. 8 hundreds × 7 = 56 hundreds, because 8 × 7 = 56.8 × 7 = 56, so 8 hundreds × 7 = 56 hundreds
- Change 56 hundreds back to a number. 1 hundred is 100, so 56 hundreds is 56 × 100. 56 hundreds = 5,600
- Write the answer. 800 × 7 = 5,600
Check. Divide back: 5,600 ÷ 7 = 800. ✓
Watch out. The answer is 56 hundreds, which has 2 zeros on the end. Count the zeros carefully.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 56 ÷ 7 = 8, and place value. 560 is 56 tens, so the answer is 8 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.56 ÷ 7 = 8
- Say the big number in tens. 560 is 56 tens.560 = 56 tens
- Divide, using the known fact. 56 tens ÷ 7 = 8 tens, because 56 ÷ 7 = 8.56 ÷ 7 = 8, so 56 tens ÷ 7 = 8 tens
- Change 8 tens back to a number. Put the zeros back.8 tens = 80
- Write the answer. 560 ÷ 7 = 80
Check. Multiply back: 80 × 7 = 560. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 56 ÷ 8 = 7, and place value. 560 is 56 tens, so the answer is 7 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.56 ÷ 8 = 7
- Say the big number in tens. 560 is 56 tens.560 = 56 tens
- Divide, using the known fact. 56 tens ÷ 8 = 7 tens, because 56 ÷ 8 = 7.56 ÷ 8 = 7, so 56 tens ÷ 8 = 7 tens
- Change 7 tens back to a number. Put the zeros back.7 tens = 70
- Write the answer. 560 ÷ 8 = 70
Check. Multiply back: 70 × 8 = 560. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 56 ÷ 8 = 7, and place value. 5,600 is 56 hundreds, so the answer is 7 hundreds.
- Spot the fact you know. Take away the zeros and look at the digits that are left.56 ÷ 8 = 7
- Say the big number in hundreds. 5,600 is 56 hundreds.5,600 = 56 hundreds
- Divide, using the known fact. 56 hundreds ÷ 8 = 7 hundreds, because 56 ÷ 8 = 7.56 ÷ 8 = 7, so 56 hundreds ÷ 8 = 7 hundreds
- Change 7 hundreds back to a number. Put the zeros back.7 hundreds = 700
- Write the answer. 5,600 ÷ 8 = 700
Check. Multiply back: 700 × 8 = 5,600. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 3 × 8 = 24, and place value. 30 is 3 tens, so the answer is 24 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.3 × 8 = 24
- Say the bigger number in tens. 30 is 3 tens.30 = 3 tens
- Multiply, using the known fact. 3 tens × 8 = 24 tens, because 3 × 8 = 24.3 × 8 = 24, so 3 tens × 8 = 24 tens
- Change 24 tens back to a number. 1 ten is 10, so 24 tens is 24 × 10. 24 tens = 240
- Write the answer. 30 × 8 = 240
Check. Divide back: 240 ÷ 8 = 30. ✓
Watch out. The answer is 24 tens, which has 1 zero on the end. Count the zeros carefully.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 7 × 5 = 35, and place value. 50 is 5 tens, so the answer is 35 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.7 × 5 = 35
- Say the bigger number in tens. 50 is 5 tens.50 = 5 tens
- Multiply, using the known fact. 5 tens × 7 = 35 tens, because 5 × 7 = 35.5 × 7 = 35, so 5 tens × 7 = 35 tens
- Change 35 tens back to a number. 1 ten is 10, so 35 tens is 35 × 10. 35 tens = 350
- Write the answer. 7 × 50 = 350
Check. Divide back: 350 ÷ 50 = 7. ✓
Watch out. The answer is 35 tens, which has 1 zero on the end. Count the zeros carefully.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 9 × 6 = 54, and place value. 90 is 9 tens, so the answer is 54 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.9 × 6 = 54
- Say the bigger number in tens. 90 is 9 tens.90 = 9 tens
- Multiply, using the known fact. 9 tens × 6 = 54 tens, because 9 × 6 = 54.9 × 6 = 54, so 9 tens × 6 = 54 tens
- Change 54 tens back to a number. 1 ten is 10, so 54 tens is 54 × 10. 54 tens = 540
- Write the answer. 90 × 6 = 540
Check. Divide back: 540 ÷ 6 = 90. ✓
Watch out. The answer is 54 tens, which has 1 zero on the end. Count the zeros carefully.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 4 × 7 = 28, and place value. 700 is 7 hundreds, so the answer is 28 hundreds.
- Spot the fact you know. Take away the zeros and look at the digits that are left.4 × 7 = 28
- Say the bigger number in hundreds. 700 is 7 hundreds.700 = 7 hundreds
- Multiply, using the known fact. 7 hundreds × 4 = 28 hundreds, because 7 × 4 = 28.7 × 4 = 28, so 7 hundreds × 4 = 28 hundreds
- Change 28 hundreds back to a number. 1 hundred is 100, so 28 hundreds is 28 × 100. 28 hundreds = 2,800
- Write the answer. 4 × 700 = 2,800
Check. Divide back: 2,800 ÷ 700 = 4. ✓
Watch out. The answer is 28 hundreds, which has 2 zeros on the end. Count the zeros carefully.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 11 × 3 = 33, and place value. 110 is 11 tens, so the answer is 33 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.11 × 3 = 33
- Say the bigger number in tens. 110 is 11 tens.110 = 11 tens
- Multiply, using the known fact. 11 tens × 3 = 33 tens, because 11 × 3 = 33.11 × 3 = 33, so 11 tens × 3 = 33 tens
- Change 33 tens back to a number. 1 ten is 10, so 33 tens is 33 × 10. 33 tens = 330
- Write the answer. 110 × 3 = 330
Check. Divide back: 330 ÷ 3 = 110. ✓
Watch out. The answer is 33 tens, which has 1 zero on the end. Count the zeros carefully.
Key words. A known fact is a multiplication fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 8 × 9 = 72, and place value. 90 is 9 tens, so the answer is 72 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.8 × 9 = 72
- Say the bigger number in tens. 90 is 9 tens.90 = 9 tens
- Multiply, using the known fact. 9 tens × 8 = 72 tens, because 9 × 8 = 72.9 × 8 = 72, so 9 tens × 8 = 72 tens
- Change 72 tens back to a number. 1 ten is 10, so 72 tens is 72 × 10. 72 tens = 720
- Write the answer. 8 × 90 = 720
Check. Divide back: 720 ÷ 90 = 8. ✓
Watch out. The answer is 72 tens, which has 1 zero on the end. Count the zeros carefully.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 36 ÷ 6 = 6, and place value. 360 is 36 tens, so the answer is 6 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.36 ÷ 6 = 6
- Say the big number in tens. 360 is 36 tens.360 = 36 tens
- Divide, using the known fact. 36 tens ÷ 6 = 6 tens, because 36 ÷ 6 = 6.36 ÷ 6 = 6, so 36 tens ÷ 6 = 6 tens
- Change 6 tens back to a number. Put the zeros back.6 tens = 60
- Write the answer. 360 ÷ 6 = 60
Check. Multiply back: 60 × 6 = 360. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 48 ÷ 8 = 6, and place value. 480 is 48 tens, so the answer is 6 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.48 ÷ 8 = 6
- Say the big number in tens. 480 is 48 tens.480 = 48 tens
- Divide, using the known fact. 48 tens ÷ 8 = 6 tens, because 48 ÷ 8 = 6.48 ÷ 8 = 6, so 48 tens ÷ 8 = 6 tens
- Change 6 tens back to a number. Put the zeros back.6 tens = 60
- Write the answer. 480 ÷ 8 = 60
Check. Multiply back: 60 × 8 = 480. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 21 ÷ 7 = 3, and place value. 2,100 is 21 hundreds, so the answer is 3 hundreds.
- Spot the fact you know. Take away the zeros and look at the digits that are left.21 ÷ 7 = 3
- Say the big number in hundreds. 2,100 is 21 hundreds.2,100 = 21 hundreds
- Divide, using the known fact. 21 hundreds ÷ 7 = 3 hundreds, because 21 ÷ 7 = 3.21 ÷ 7 = 3, so 21 hundreds ÷ 7 = 3 hundreds
- Change 3 hundreds back to a number. Put the zeros back.3 hundreds = 300
- Write the answer. 2,100 ÷ 7 = 300
Check. Multiply back: 300 × 7 = 2,100. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 54 ÷ 9 = 6, and place value. 5,400 is 54 hundreds, so the answer is 6 hundreds.
- Spot the fact you know. Take away the zeros and look at the digits that are left.54 ÷ 9 = 6
- Say the big number in hundreds. 5,400 is 54 hundreds.5,400 = 54 hundreds
- Divide, using the known fact. 54 hundreds ÷ 9 = 6 hundreds, because 54 ÷ 9 = 6.54 ÷ 9 = 6, so 54 hundreds ÷ 9 = 6 hundreds
- Change 6 hundreds back to a number. Put the zeros back.6 hundreds = 600
- Write the answer. 5,400 ÷ 9 = 600
Check. Multiply back: 600 × 9 = 5,400. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 88 ÷ 11 = 8, and place value. 880 is 88 tens, so the answer is 8 tens.
- Spot the fact you know. Take away the zeros and look at the digits that are left.88 ÷ 11 = 8
- Say the big number in tens. 880 is 88 tens.880 = 88 tens
- Divide, using the known fact. 88 tens ÷ 11 = 8 tens, because 88 ÷ 11 = 8.88 ÷ 11 = 8, so 88 tens ÷ 11 = 8 tens
- Change 8 tens back to a number. Put the zeros back.8 tens = 80
- Write the answer. 880 ÷ 11 = 80
Check. Multiply back: 80 × 11 = 880. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A known fact is a fact you can already recall. A derived fact is a new fact you work out from a known fact.
Method. Use the fact you know, 12 ÷ 12 = 1, and place value. 1,200 is 12 hundreds, so the answer is 1 hundreds.
- Spot the fact you know. Take away the zeros and look at the digits that are left.12 ÷ 12 = 1
- Say the big number in hundreds. 1,200 is 12 hundreds.1,200 = 12 hundreds
- Divide, using the known fact. 12 hundreds ÷ 12 = 1 hundreds, because 12 ÷ 12 = 1.12 ÷ 12 = 1, so 12 hundreds ÷ 12 = 1 hundreds
- Change 1 hundreds back to a number. Put the zeros back.1 hundreds = 100
- Write the answer. 1,200 ÷ 12 = 100
Check. Multiply back: 100 × 12 = 1,200. ✓
Watch out. Keep the zeros. 420 ÷ 7 is 60, not 6.
Key words. A derived fact is a new fact you work out from a fact you already know.
Method. 6 is one more than 5, so add one more group of 8 to the answer to 5 × 8.
- Write the fact you know. We start from the fact we know.5 × 8 = 40
- Compare 6 with 5. 6 is one more than 5, so we need one more group of 8.6 = 5 + 1
- Add one more group. One group is 8.40 + 8 = 48
- Write the answer. 6 × 8 = 48
Check. Check by dividing: 48 ÷ 8 = 6. ✓
Watch out. Add 8, the size of one group, not 6 or 1.
Key words. A derived fact is a new fact you work out from a fact you already know.
Method. 4 is one less than 5, so take away one group of 8 from the answer to 5 × 8.
- Write the fact you know. We start from the fact we know.5 × 8 = 40
- Compare 4 with 5. 4 is one less than 5, so we need one group of 8 fewer.4 = 5 − 1
- Take away one group. One group is 8.40 − 8 = 32
- Write the answer. 4 × 8 = 32
Check. Check by dividing: 32 ÷ 8 = 4. ✓
Watch out. Take away 8, the size of one group, not 4 or 1.
Key words. A derived fact is a new fact you work out from a fact you already know.
Method. 10 is double 5, so double the answer to 5 × 8.
- Write the fact you know. We start from the fact we know.5 × 8 = 40
- Compare 10 with 5. 10 is double 5, so 10 groups of 8 are double 5 groups of 8.10 = 2 × 5
- Double the known answer. double 40 = 80
- Write the answer. 10 × 8 = 80
Check. Check by dividing: 80 ÷ 8 = 10. ✓
Watch out. Doubling the number of groups doubles the total. Do not double the other number as well.
Key words. A derived fact is a new fact you work out from a fact you already know.
Method. 6 is double 3, so double the answer to 3 × 9.
- Write the fact you know. We start from the fact we know.3 × 9 = 27
- Compare 6 with 3. 6 is double 3, so 6 groups of 9 are double 3 groups of 9.6 = 2 × 3
- Double the known answer. double 20 = 40, double 7 = 14, so 40 + 14 = 54
- Write the answer. 6 × 9 = 54
Check. Check by dividing: 54 ÷ 9 = 6. ✓
Watch out. Doubling the number of groups doubles the total. Do not double the other number as well.
Key words. A derived fact is a new fact you work out from a fact you already know.
Method. 6 is half of 12, so halve the answer to 12 × 5.
- Write the fact you know. We start from the fact we know.12 × 5 = 60
- Compare 6 with 12. 6 is half of 12, so 6 groups of 5 are half of 12 groups of 5.6 = 12 ÷ 2
- Halve the known answer. half of 60 = 30
- Write the answer. 6 × 5 = 30
Check. Check by dividing: 30 ÷ 5 = 6. ✓
Watch out. Halving the number of groups halves the total.
Key words. A derived fact is a new fact you work out from a fact you already know.
Method. 8 is double 4, so double the answer to 4 × 7.
- Write the fact you know. We start from the fact we know.4 × 7 = 28
- Compare 8 with 4. 8 is double 4, so 8 groups of 7 are double 4 groups of 7.8 = 2 × 4
- Double the known answer. double 20 = 40, double 8 = 16, so 40 + 16 = 56
- Write the answer. 8 × 7 = 56
Check. Check by dividing: 56 ÷ 7 = 8. ✓
Watch out. Doubling the number of groups doubles the total. Do not double the other number as well.
Key words. A derived fact is a new fact you work out from a fact you already know.
Method. 6 is half of 12, so halve the answer to 12 × 6.
- Write the fact you know. We start from the fact we know.12 × 6 = 72
- Compare 6 with 12. 6 is half of 12, so 6 groups of 6 are half of 12 groups of 6.6 = 12 ÷ 2
- Halve the known answer. half of 60 = 30, half of 12 = 6, so 30 + 6 = 36
- Write the answer. 6 × 6 = 36
Check. Check by dividing: 36 ÷ 6 = 6. ✓
Watch out. Halving the number of groups halves the total.
Method. There are 8 equal groups, so multiply the number in one group by the number of groups.
- Draw a bar model. 8 equal bars show 8 equal groups. Each bar is 60p. We want the total.
- Choose the operation. Equal groups: multiply the number of groups by the amount in each group.8 × 60p
- Work it out. Use a times table trick.6 × 8 = 48
60 is 6 tens, so 8 × 6 tens = 48 tens = 480 - Write the answer. Include the unit.480p
Check. Divide back: 480 ÷ 8 = 60. ✓
Watch out. Check that you multiplied. Equal groups mean the total is bigger than the size of one group.
Method. There are 6 equal groups, so multiply the number in one group by the number of groups.
- Draw a bar model. 6 equal bars show 6 equal buses. Each bar is 70. We want the total.
- Choose the operation. Equal groups: multiply the number of groups by the amount in each group.6 × 70
- Work it out. Use a times table trick.6 × 7 = 42
70 is 7 tens, so 6 × 7 tens = 42 tens = 420 - Write the answer. Include the unit.420 passengers
Check. Divide back: 420 ÷ 6 = 70. ✓
Watch out. Check that you multiplied. Equal groups mean the total is bigger than the size of one group.
Method. Dividing is the opposite of multiplying. Use the times table to find how many times the number fits.
- Draw a bar model. The whole is 540. Each bar is 9. We want to know how many bars. (The picture shows only some of the bars.)
- Choose the operation. We want to know how many groups of 9 fit into 540. That is a division.540 ÷ 9
- Use the times tables. Think: what do we multiply 9 by to get 540?54 ÷ 9 = 6
540 is 54 tens, so 54 tens ÷ 9 = 6 tens = 60 - Write the answer. Include the unit.60 boxes
Check. Multiply back: 60 × 9 = 540. ✓
Watch out. Read the question carefully. Does it ask for the size of each group, or for how many groups?
Method. Check Zoe’s answer. She used the right fact, but what has happened to the zero?
- Zoe’s fact. 6 × 7 = 42 is correct.6 × 7 = 42
- Look at 60. 60 is not 6. It is 6 tens, so the answer is 42 tens, not 42 ones.6 tens × 7 = 42 tens
- Write 42 tens as a number. 42 tens = 42 × 10.42 tens = 420
- Answer. 60 × 7 = 420
Check. Estimate: 60 × 7 is about 60 × 10 = 600, so the answer must be about 600, not 42. ✓
Watch out. Zoe forgot the zero. Always put the zeros back at the end.
Method. Work out each one. The odd one out has a different answer from the others.
- Work out A and B. Use 6 × 7 = 42 and put the zero back.6 × 70 = 420 60 × 7 = 420
- Work out C. Multiplying by 10 moves the digits one place left.42 × 10 = 420
- Work out D. 600 is 6 hundreds, so the answer is 42 hundreds.600 × 7 = 4,200
- Choose the odd one out. A, B and C are all 420.D
Check. 4,200 ÷ 7 = 600. ✓
Watch out. Count the zeros: A, B and C each have one zero in total in the numbers multiplied. D has two.
Method. A multiple of 10 is a number of tens. Think about what happens to the ones digit.
- Try some examples. Pick different multiples of 10.30 × 7 = 210 50 × 3 = 150 80 × 9 = 720
- Explain why. A multiple of 10 is a number of tens. A number of tens times a whole number is still a number of tens, and tens have 0 ones.So the ones digit is always 0.
- Decide. Always
Check. Check with an odd times: 70 × 5 = 350. It ends in 0. ✓
Watch out. This does not work the other way. Not every number that ends in 0 is a multiple of 10 times a fact you know, but they are all multiples of 10.
Method. 5,600 is 56 hundreds. So use 56 as a fact, then change the units to hundreds.
- Write the fact you know. 7 × 8 = 56
- Say 5,600 in hundreds. 5,600 is 56 hundreds.5,600 = 56 hundreds
- Write four facts. The hundreds go with one of the numbers each time.700 × 8 = 5,600
8 × 700 = 5,600
5,600 ÷ 8 = 700
5,600 ÷ 7 = 800
Check. Check one: 700 × 8 = 7 hundreds × 8 = 56 hundreds = 5,600. ✓
Watch out. There are more answers too, such as 800 × 7 = 5,600. Any correct fact is fine.
Exercise 3H Multiplication and division problems
Non-calculatorMethod. There are 7 equal groups, so multiply the number in one group by the number of groups.
- Draw a bar model. 7 equal bars show 7 equal years. Each bar is 12. We want the total.
- Choose the operation. Equal groups: multiply the number of groups by the amount in each group.7 × 12
- Work it out. Use a times table trick.10 × 7 = 70
7 + 7 = 14
70 + 14 = 84
7 × 12 = 84 - Write the answer. Include the unit.84 months
Check. Divide back: 84 ÷ 7 = 12. ✓
Watch out. Check that you multiplied. Equal groups mean the total is bigger than the size of one group.
Method. Dividing is the opposite of multiplying. Use the times table to find how many times the number fits.
- Draw a bar model. The whole is 60. It is split into 5 equal parts. We want the size of one part.
- Choose the operation. Sharing equally means dividing.60 ÷ 5
- Use the times tables. Think: what do we multiply 5 by to get 60?12 × 5 = 60, so 60 ÷ 5 = 12
- Write the answer. Include the unit.12 stickers
Check. Multiply back: 12 × 5 = 60. ✓
Watch out. Read the question carefully. Does it ask for the size of each group, or for how many groups?
Method. There are 12 equal groups, so multiply the number in one group by the number of groups.
- Draw a bar model. 12 equal bars show 12 equal books. Each bar is £8. We want the total.
- Choose the operation. Equal groups: multiply the number of groups by the amount in each group.12 × £8
- Work it out. Use a times table trick.10 × 8 = 80
8 + 8 = 16
80 + 16 = 96
12 × 8 = 96 - Write the answer. Include the unit.£96
Check. Divide back: 96 ÷ 12 = 8. ✓
Watch out. Check that you multiplied. Equal groups mean the total is bigger than the size of one group.
Method. Dividing is the opposite of multiplying. Use the times table to find how many times the number fits.
- Draw a bar model. The whole is 99. Each bar is 9. We want to know how many bars. (The picture shows only some of the bars.)
- Choose the operation. We want to know how many groups of 9 fit into 99. That is a division.99 ÷ 9
- Use the times tables. Think: what do we multiply 9 by to get 99?11 × 9 = 99, so 99 ÷ 9 = 11
- Write the answer. Include the unit.11 pots
Check. Multiply back: 11 × 9 = 99. ✓
Watch out. Read the question carefully. Does it ask for the size of each group, or for how many groups?
Method. Two steps. First multiply to find how many stickers Aisha has. Then take away the stickers she gives away.
- Draw a bar model for step 1. 4 equal packs of 12 stickers.
- Step 1: multiply. Equal groups, so multiply.double 10 = 20, double 2 = 4, so 20 + 4 = 24
double 20 = 40, double 4 = 8, so 40 + 8 = 48
4 × 12 = 48 - Step 2: take away. Aisha gives away 15. Take away 10, then 5.48 − 10 = 38, then 38 − 5 = 33
- Write the answer. 33 stickers
Check. Add back: 33 + 15 = 48 and 48 ÷ 4 = 12. ✓
Watch out. Do both steps. 48 is the number she starts with, not the number she has left.
Method. Two steps. First find the total cost of the cakes. Then take it away from the money Leo pays with to find the change.
- Step 1: multiply. 7 cakes at £6 each.5 × 7 = 35
35 + 7 = 42
7 × 6 = 42 - Step 2: find the change. Change = money paid − cost.£50 − £42: 42 + 8 = 50, so the change is £8
- Write the answer. £8
Check. Add up: £42 + £8 = £50. ✓
Watch out. The change is what is left, not the cost of the cakes.
Method. There are two kinds of box, so work out the markers in each kind and add the two totals.
- Boxes of 8 markers. 5 boxes of 8.10 × 8 = 80
half of 80 = 40
5 × 8 = 40 - Boxes of 12 markers. 3 boxes of 12.double 10 = 20, double 2 = 4, so 20 + 4 = 24
24 + 12 = 36
3 × 12 = 36 - Add the two totals. 40 + 36 = 76
- Write the answer. 76 markers
Check. Take away one total: 76 − 40 = 36. ✓
Watch out. Do not multiply all four numbers together. Multiply in pairs and then add.
Method. Work out how many pages each child reads, then compare the two totals.
- Mei’s pages. 7 pages a day for 12 days.10 × 7 = 70
7 + 7 = 14
70 + 14 = 84
7 × 12 = 84 - Ben’s pages. 9 pages a day for 9 days.10 × 9 = 90
90 − 9 = 81
9 × 9 = 81 - Compare. Find the difference between 84 and 81.84 − 81 = 3
- Write the answer. Mei reads 3 more pages.
Check. 81 + 3 = 84. ✓
Watch out. The question asks “how many more”, so you need the difference, not just who reads more.
| Cards | Price of one pack |
|---|---|
| Football | £4 |
| Animals | £7 |
Sam buys 8 packs of football cards and 6 packs of animal cards. How much does he spend?
Method. Work out the cost of each kind of cards, then add.
- Football cards. 8 packs at £4 each.8 + 8 = 16
double 10 = 20, double 6 = 12, so 20 + 12 = 32
8 × 4 = 32 - Animal cards. 6 packs at £7 each.5 × 7 = 35
35 + 7 = 42
6 × 7 = 42 - Add the two costs. £32 + £42 = £74
- Write the answer. £74
Check. £74 − £32 = £42. ✓
Watch out. Multiply first, then add. Do not add the prices first.
Method. Look at how many bars each model has and what each bar shows.
- Read the question. 9 rows, and each row has 7 seats. So there are 9 equal groups of 7.Model should have 9 bars of 7.
- Choose the model. Model A has 9 bars labelled 7. Model B has 7 bars labelled 9.Model A matches.
- Work out both totals. Multiplication can be done in either order.9 × 7 = 63 and 7 × 9 = 63
- Answer the question. Yes. Both are 63 because 9 × 7 = 7 × 9.
Check. Turn the seats on their side: 7 rows of 9 seats is the same seats. ✓
Watch out. The models are different pictures of different groups, but they have the same total.
Method. Work out both. Then show why they must be the same with an array.
- Work out 8 packs of 6. Double three times.6 + 6 = 12
double 10 = 20, double 2 = 4, so 20 + 4 = 24
double 20 = 40, double 4 = 8, so 40 + 8 = 48
8 × 6 = 48 - Work out 6 packs of 8. This is the same two numbers the other way round.6 + 6 = 12
double 10 = 20, double 2 = 4, so 20 + 4 = 24
double 20 = 40, double 4 = 8, so 40 + 8 = 48
6 × 8 = 48 - Use the arrays to explain. Turning the first array on its side gives the second array. No dots are added or lost.8 × 6 = 6 × 8 = 48
- Answer. Yes, Anil is right.
Check. 48 ÷ 6 = 8 and 48 ÷ 8 = 6. ✓
Watch out. This is commutativity. It works for any two numbers that are multiplied.
A 6 bags have 9 apples in each bag. How many apples are there?
B 42 pens are shared equally between 6 children. How many pens does each child get?
C A rope 56 m long is cut into pieces that are each 7 m long. How many pieces are there?
D A train has 8 carriages with 12 seats in each carriage. How many seats are there?
Method. For each problem, ask: do I know the total? If the total is known and I need to share it or split it, divide. If I know the size of each group and the number of groups, multiply.
- Problem A. 6 groups of 9 and the total is not known.Multiply: 6 × 9
- Problem B. The total, 42, is shared equally between 6.Divide: 42 ÷ 6
- Problem C. The total length, 56 m, is split into pieces of 7 m. How many fit?Divide: 56 ÷ 7
- Problem D. 8 groups of 12 and the total is not known.Multiply: 8 × 12
- Choose. B and C
Check. 42 ÷ 6 = 7 and 56 ÷ 7 = 8. Both are easy to check by multiplying. ✓
Watch out. Do not choose by looking for one word. “Shared” and “cut into” both mean divide here.
Method. Try different numbers of cows. For each try, work out the number of chickens (10 minus the cows) and count all the legs.
- Make a table. Chickens = 10 − cows. Legs = 2 × chickens + 4 × cows.
Chickens Cows Chicken legs Cow legs Total legs 8 2 16 8 24 7 3 14 12 26 6 4 12 16 28 5 5 10 20 30 - Look at the totals. We want exactly 28 legs. Too few legs means we need more cows.With 4 cows: 6 chickens have 12 legs, 4 cows have 16 legs. 12 + 16 = 28.
- Write the answer. 6 chickens and 4 cows
Check. 6 + 4 = 10 animals. 6 × 2 = 12 and 4 × 4 = 16. 12 + 16 = 28 legs. ✓
Watch out. Check both facts: the number of animals and the number of legs.
Exercise 3I Times tables check practice: 25 questions, 6 seconds each
Non-calculatorMethod. Multiplying by 2 is the same as doubling. Double the number.
- Swap the numbers round. Order does not matter in multiplication, so 9 × 2 = 2 × 9. Use the 2 times table trick.9 × 2 = 2 × 9
- Double the number. Doubling means adding the number to itself.9 + 9 = 18
- Write the answer. 9 × 2 = 18
Check. The digits of 18 add up to 9: 1 + 8 = 9. ✓
Watch out. Doubling is not adding 2. To double 7, add 7 + 7, not 7 + 2.
Method. Five is half of ten. Multiply by 10 first, then halve the answer.
- Multiply by 10. This is easy: move the digits one place to the left.10 × 4 = 40
- Halve the answer. 5 is half of 10, so 5 lots of a number is half of 10 lots.half of 40 = 20
- Write the answer. Answers in the 5 times table end in 0 or 5.5 × 4 = 20
Check. Check by dividing: 20 ÷ 4 = 5. ✓
Watch out. Halve the answer to 10 × the number. Do not halve the number before you multiply by 10 and then forget to multiply.
Method. Three is double and one more. Double the number, then add the number once.
- Double the number. This gives 2 lots.3 + 3 = 6
- Add one more group. 3 = 2 + 1, so add the number once more.6 + 3 = 9
- Write the answer. 3 × 3 = 9
Check. Check by dividing: 9 ÷ 3 = 3. ✓
Watch out. Add the number itself, not 3, as the extra group.
Method. Eleven is ten and one more. Multiply by 10, then add one more group.
- Swap the numbers round. Order does not matter in multiplication, so 4 × 11 = 11 × 4. Use the 11 times table trick.4 × 11 = 11 × 4
- Multiply by 10. 10 lots of the number first.10 × 4 = 40
- Add one more group. 11 = 10 + 1, so add the number itself once more. You can also write the digit twice: 44.40 + 4 = 44
- Write the answer. 4 × 11 = 44
Check. Check by dividing: 44 ÷ 4 = 11. ✓
Watch out. The “write the digit twice” trick only works from 11 × 1 to 11 × 9. For 11 × 12 it does not give 1212. Use 10 lots + 1 lot.
Method. Multiplying by 2 is the same as doubling. Double the number.
- Swap the numbers round. Order does not matter in multiplication, so 11 × 2 = 2 × 11. Use the 2 times table trick.11 × 2 = 2 × 11
- Double the number. Doubling means adding the number to itself.double 10 = 20, double 1 = 2, so 20 + 2 = 22
- Write the answer. 11 × 2 = 22
Check. Check by dividing: 22 ÷ 2 = 11. ✓
Watch out. Doubling is not adding 2. To double 7, add 7 + 7, not 7 + 2.
Method. Five is half of ten. Multiply by 10 first, then halve the answer.
- Swap the numbers round. Order does not matter in multiplication, so 3 × 5 = 5 × 3. Use the 5 times table trick.3 × 5 = 5 × 3
- Multiply by 10. This is easy: move the digits one place to the left.10 × 3 = 30
- Halve the answer. 5 is half of 10, so 5 lots of a number is half of 10 lots.half of 20 = 10, half of 10 = 5, so 10 + 5 = 15
- Write the answer. Answers in the 5 times table end in 0 or 5.3 × 5 = 15
Check. Check by dividing: 15 ÷ 3 = 5. ✓
Watch out. Halve the answer to 10 × the number. Do not halve the number before you multiply by 10 and then forget to multiply.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Think about tens. 10 × 5 means 5 lots of 10, which is 5 tens.5 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.5 → 50
- Write the answer. 10 × 5 = 50
Check. Check by dividing: 50 ÷ 5 = 10. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Swap the numbers round. Order does not matter in multiplication, so 3 × 10 = 10 × 3. Use the 10 times table trick.3 × 10 = 10 × 3
- Think about tens. 10 × 3 means 3 lots of 10, which is 3 tens.3 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.3 → 30
- Write the answer. 3 × 10 = 30
Check. Check by dividing: 30 ÷ 3 = 10. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. Five is half of ten. Multiply by 10 first, then halve the answer.
- Swap the numbers round. Order does not matter in multiplication, so 7 × 5 = 5 × 7. Use the 5 times table trick.7 × 5 = 5 × 7
- Multiply by 10. This is easy: move the digits one place to the left.10 × 7 = 70
- Halve the answer. 5 is half of 10, so 5 lots of a number is half of 10 lots.half of 60 = 30, half of 10 = 5, so 30 + 5 = 35
- Write the answer. Answers in the 5 times table end in 0 or 5.7 × 5 = 35
Check. Check by dividing: 35 ÷ 5 = 7. ✓
Watch out. Halve the answer to 10 × the number. Do not halve the number before you multiply by 10 and then forget to multiply.
Method. Four is double double. Double the number, then double the answer.
- Swap the numbers round. Order does not matter in multiplication, so 8 × 4 = 4 × 8. Use the 4 times table trick.8 × 4 = 4 × 8
- Double the number. This gives 2 lots.8 + 8 = 16
- Double the answer again. Doubling twice gives 4 lots.double 10 = 20, double 6 = 12, so 20 + 12 = 32
- Write the answer. 8 × 4 = 32
Check. Check by dividing: 32 ÷ 4 = 8. ✓
Watch out. You must double twice. Doubling once gives the 2 times table.
Method. Five is half of ten. Multiply by 10 first, then halve the answer.
- Multiply by 10. This is easy: move the digits one place to the left.10 × 11 = 110
- Halve the answer. 5 is half of 10, so 5 lots of a number is half of 10 lots.half of 100 = 50, half of 10 = 5, so 50 + 5 = 55
- Write the answer. Answers in the 5 times table end in 0 or 5.5 × 11 = 55
Check. Check by dividing: 55 ÷ 5 = 11. ✓
Watch out. Halve the answer to 10 × the number. Do not halve the number before you multiply by 10 and then forget to multiply.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Think about tens. 10 × 11 means 11 lots of 10, which is 11 tens.11 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.11 → 110
- Write the answer. 10 × 11 = 110
Check. Check by dividing: 110 ÷ 10 = 11. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. Multiplying by 2 is the same as doubling. Double the number.
- Swap the numbers round. Order does not matter in multiplication, so 4 × 2 = 2 × 4. Use the 2 times table trick.4 × 2 = 2 × 4
- Double the number. Doubling means adding the number to itself.4 + 4 = 8
- Write the answer. 4 × 2 = 8
Check. Check by dividing: 8 ÷ 2 = 4. ✓
Watch out. Doubling is not adding 2. To double 7, add 7 + 7, not 7 + 2.
Method. Four is double double. Double the number, then double the answer.
- Swap the numbers round. Order does not matter in multiplication, so 3 × 4 = 4 × 3. Use the 4 times table trick.3 × 4 = 4 × 3
- Double the number. This gives 2 lots.3 + 3 = 6
- Double the answer again. Doubling twice gives 4 lots.6 + 6 = 12
- Write the answer. 3 × 4 = 12
Check. Check by dividing: 12 ÷ 3 = 4. ✓
Watch out. You must double twice. Doubling once gives the 2 times table.
Method. Multiplying by 2 is the same as doubling. Double the number.
- Double the number. Doubling means adding the number to itself.5 + 5 = 10
- Write the answer. 2 × 5 = 10
Check. Check by dividing: 10 ÷ 2 = 5. ✓
Watch out. Doubling is not adding 2. To double 7, add 7 + 7, not 7 + 2.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Think about tens. 10 × 9 means 9 lots of 10, which is 9 tens.9 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.9 → 90
- Write the answer. 10 × 9 = 90
Check. The digits of 90 add up to 9: 9 + 0 = 9. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. Three is double and one more. Double the number, then add the number once.
- Double the number. This gives 2 lots.7 + 7 = 14
- Add one more group. 3 = 2 + 1, so add the number once more.14 + 7 = 21
- Write the answer. 3 × 7 = 21
Check. Check by dividing: 21 ÷ 3 = 7. ✓
Watch out. Add the number itself, not 3, as the extra group.
Method. Nine is one less than ten. Multiply by 10, then take away one group.
- Multiply by 10. 10 lots of the number first.10 × 3 = 30
- Take away one group. 9 = 10 − 1, so take away the number itself once.30 − 3 = 27
- Write the answer. Answers in the 9 times table have digits that add up to 9 (or 18).9 × 3 = 27
Check. The digits of 27 add up to 9: 2 + 7 = 9. ✓
Watch out. Take away 3, the other number, not 9. For 9 × 3 you work out 10 × 3 − 3.
Method. Four is double double. Double the number, then double the answer.
- Swap the numbers round. Order does not matter in multiplication, so 6 × 4 = 4 × 6. Use the 4 times table trick.6 × 4 = 4 × 6
- Double the number. This gives 2 lots.6 + 6 = 12
- Double the answer again. Doubling twice gives 4 lots.double 10 = 20, double 2 = 4, so 20 + 4 = 24
- Write the answer. 6 × 4 = 24
Check. Check by dividing: 24 ÷ 4 = 6. ✓
Watch out. You must double twice. Doubling once gives the 2 times table.
Method. Five is half of ten. Multiply by 10 first, then halve the answer.
- Multiply by 10. This is easy: move the digits one place to the left.10 × 9 = 90
- Halve the answer. 5 is half of 10, so 5 lots of a number is half of 10 lots.half of 80 = 40, half of 10 = 5, so 40 + 5 = 45
- Write the answer. Answers in the 5 times table end in 0 or 5.5 × 9 = 45
Check. The digits of 45 add up to 9: 4 + 5 = 9. ✓
Watch out. Halve the answer to 10 × the number. Do not halve the number before you multiply by 10 and then forget to multiply.
Method. Eleven is ten and one more. Multiply by 10, then add one more group.
- Multiply by 10. 10 lots of the number first.10 × 3 = 30
- Add one more group. 11 = 10 + 1, so add the number itself once more. You can also write the digit twice: 33.30 + 3 = 33
- Write the answer. 11 × 3 = 33
Check. Check by dividing: 33 ÷ 3 = 11. ✓
Watch out. The “write the digit twice” trick only works from 11 × 1 to 11 × 9. For 11 × 12 it does not give 1212. Use 10 lots + 1 lot.
Method. Four is double double. Double the number, then double the answer.
- Double the number. This gives 2 lots.4 + 4 = 8
- Double the answer again. Doubling twice gives 4 lots.8 + 8 = 16
- Write the answer. 4 × 4 = 16
Check. Check by dividing: 16 ÷ 4 = 4. ✓
Watch out. You must double twice. Doubling once gives the 2 times table.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Swap the numbers round. Order does not matter in multiplication, so 12 × 10 = 10 × 12. Use the 10 times table trick.12 × 10 = 10 × 12
- Think about tens. 10 × 12 means 12 lots of 10, which is 12 tens.12 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.12 → 120
- Write the answer. 12 × 10 = 120
Check. Check by dividing: 120 ÷ 10 = 12. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. Eleven is ten and one more. Multiply by 10, then add one more group.
- Swap the numbers round. Order does not matter in multiplication, so 8 × 11 = 11 × 8. Use the 11 times table trick.8 × 11 = 11 × 8
- Multiply by 10. 10 lots of the number first.10 × 8 = 80
- Add one more group. 11 = 10 + 1, so add the number itself once more. You can also write the digit twice: 88.80 + 8 = 88
- Write the answer. 8 × 11 = 88
Check. Check by dividing: 88 ÷ 8 = 11. ✓
Watch out. The “write the digit twice” trick only works from 11 × 1 to 11 × 9. For 11 × 12 it does not give 1212. Use 10 lots + 1 lot.
Method. Four is double double. Double the number, then double the answer.
- Double the number. This gives 2 lots.double 10 = 20, double 2 = 4, so 20 + 4 = 24
- Double the answer again. Doubling twice gives 4 lots.double 20 = 40, double 4 = 8, so 40 + 8 = 48
- Write the answer. 4 × 12 = 48
Check. Check by dividing: 48 ÷ 4 = 12. ✓
Watch out. You must double twice. Doubling once gives the 2 times table.
Method. Three is double and one more. Double the number, then add the number once.
- Double the number. This gives 2 lots.7 + 7 = 14
- Add one more group. 3 = 2 + 1, so add the number once more.14 + 7 = 21
- Write the answer. 3 × 7 = 21
Check. Check by dividing: 21 ÷ 3 = 7. ✓
Watch out. Add the number itself, not 3, as the extra group.
Method. Eleven is ten and one more. Multiply by 10, then add one more group.
- Multiply by 10. 10 lots of the number first.10 × 9 = 90
- Add one more group. 11 = 10 + 1, so add the number itself once more. You can also write the digit twice: 99.90 + 9 = 99
- Write the answer. 11 × 9 = 99
Check. The digits of 99 add up to 9: 9 + 9 = 18. ✓
Watch out. The “write the digit twice” trick only works from 11 × 1 to 11 × 9. For 11 × 12 it does not give 1212. Use 10 lots + 1 lot.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Swap the numbers round. Order does not matter in multiplication, so 8 × 10 = 10 × 8. Use the 10 times table trick.8 × 10 = 10 × 8
- Think about tens. 10 × 8 means 8 lots of 10, which is 8 tens.8 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.8 → 80
- Write the answer. 8 × 10 = 80
Check. Check by dividing: 80 ÷ 8 = 10. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. Multiplying by 2 is the same as doubling. Double the number.
- Double the number. Doubling means adding the number to itself.8 + 8 = 16
- Write the answer. 2 × 8 = 16
Check. Check by dividing: 16 ÷ 2 = 8. ✓
Watch out. Doubling is not adding 2. To double 7, add 7 + 7, not 7 + 2.
Method. Multiplying by 2 is the same as doubling. Double the number.
- Double the number. Doubling means adding the number to itself.3 + 3 = 6
- Write the answer. 2 × 3 = 6
Check. Check by dividing: 6 ÷ 2 = 3. ✓
Watch out. Doubling is not adding 2. To double 7, add 7 + 7, not 7 + 2.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Think about tens. 10 × 9 means 9 lots of 10, which is 9 tens.9 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.9 → 90
- Write the answer. 10 × 9 = 90
Check. The digits of 90 add up to 9: 9 + 0 = 9. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. Eleven is ten and one more. Multiply by 10, then add one more group.
- Multiply by 10. 10 lots of the number first.10 × 7 = 70
- Add one more group. 11 = 10 + 1, so add the number itself once more. You can also write the digit twice: 77.70 + 7 = 77
- Write the answer. 11 × 7 = 77
Check. Check by dividing: 77 ÷ 7 = 11. ✓
Watch out. The “write the digit twice” trick only works from 11 × 1 to 11 × 9. For 11 × 12 it does not give 1212. Use 10 lots + 1 lot.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Swap the numbers round. Order does not matter in multiplication, so 5 × 10 = 10 × 5. Use the 10 times table trick.5 × 10 = 10 × 5
- Think about tens. 10 × 5 means 5 lots of 10, which is 5 tens.5 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.5 → 50
- Write the answer. 5 × 10 = 50
Check. Check by dividing: 50 ÷ 5 = 10. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. Five is half of ten. Multiply by 10 first, then halve the answer.
- Multiply by 10. This is easy: move the digits one place to the left.10 × 9 = 90
- Halve the answer. 5 is half of 10, so 5 lots of a number is half of 10 lots.half of 80 = 40, half of 10 = 5, so 40 + 5 = 45
- Write the answer. Answers in the 5 times table end in 0 or 5.5 × 9 = 45
Check. The digits of 45 add up to 9: 4 + 5 = 9. ✓
Watch out. Halve the answer to 10 × the number. Do not halve the number before you multiply by 10 and then forget to multiply.
Method. Seven is five and two. Work out 5 lots and 2 lots, then add them.
- Work out 5 lots. The 5 times table is half of the 10 times table.5 × 7 = 35
- Work out 2 lots. Double the number.7 + 7 = 14
- Add them. 7 = 5 + 2.35 + 14 = 49
- Write the answer. 7 × 7 = 49
Check. Check by dividing: 49 ÷ 7 = 7. ✓
Watch out. Do not forget the 2 lots. 7 lots = 5 lots + 2 lots.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Think about tens. 10 × 11 means 11 lots of 10, which is 11 tens.11 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.11 → 110
- Write the answer. 10 × 11 = 110
Check. Check by dividing: 110 ÷ 10 = 11. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. Multiplying by 2 is the same as doubling. Double the number.
- Double the number. Doubling means adding the number to itself.5 + 5 = 10
- Write the answer. 2 × 5 = 10
Check. Check by dividing: 10 ÷ 2 = 5. ✓
Watch out. Doubling is not adding 2. To double 7, add 7 + 7, not 7 + 2.
Method. Eleven is ten and one more. Multiply by 10, then add one more group.
- Multiply by 10. 10 lots of the number first.10 × 8 = 80
- Add one more group. 11 = 10 + 1, so add the number itself once more. You can also write the digit twice: 88.80 + 8 = 88
- Write the answer. 11 × 8 = 88
Check. Check by dividing: 88 ÷ 8 = 11. ✓
Watch out. The “write the digit twice” trick only works from 11 × 1 to 11 × 9. For 11 × 12 it does not give 1212. Use 10 lots + 1 lot.
Method. Three is double and one more. Double the number, then add the number once.
- Swap the numbers round. Order does not matter in multiplication, so 6 × 3 = 3 × 6. Use the 3 times table trick.6 × 3 = 3 × 6
- Double the number. This gives 2 lots.6 + 6 = 12
- Add one more group. 3 = 2 + 1, so add the number once more.12 + 6 = 18
- Write the answer. 6 × 3 = 18
Check. Check by dividing: 18 ÷ 3 = 6. ✓
Watch out. Add the number itself, not 3, as the extra group.
Method. Five is half of ten. Multiply by 10 first, then halve the answer.
- Swap the numbers round. Order does not matter in multiplication, so 7 × 5 = 5 × 7. Use the 5 times table trick.7 × 5 = 5 × 7
- Multiply by 10. This is easy: move the digits one place to the left.10 × 7 = 70
- Halve the answer. 5 is half of 10, so 5 lots of a number is half of 10 lots.half of 60 = 30, half of 10 = 5, so 30 + 5 = 35
- Write the answer. Answers in the 5 times table end in 0 or 5.7 × 5 = 35
Check. Check by dividing: 35 ÷ 5 = 7. ✓
Watch out. Halve the answer to 10 × the number. Do not halve the number before you multiply by 10 and then forget to multiply.
Method. Three is double and one more. Double the number, then add the number once.
- Double the number. This gives 2 lots.8 + 8 = 16
- Add one more group. 3 = 2 + 1, so add the number once more.16 + 8 = 24
- Write the answer. 3 × 8 = 24
Check. Check by dividing: 24 ÷ 3 = 8. ✓
Watch out. Add the number itself, not 3, as the extra group.
Method. Twelve is ten and two. Multiply by 10, multiply by 2, then add.
- Multiply by 10. Move the digits one place to the left.10 × 6 = 60
- Multiply by 2. Double the number.6 + 6 = 12
- Add the two answers together. 12 = 10 + 2.60 + 12 = 72
- Write the answer. 12 × 6 = 72
Check. Check by dividing: 72 ÷ 6 = 12. ✓
Watch out. Do both parts, 10 lots and 2 lots, then add. Do not stop after 10 lots.
Method. Six is five and one more. Work out 5 lots, then add one more group.
- Work out 5 lots. The 5 times table is half of the 10 times table: 70 halved.5 × 7 = 35
- Add one more group. 6 = 5 + 1, so add the number once more.35 + 7 = 42
- Write the answer. 6 × 7 = 42
Check. Check by dividing: 42 ÷ 6 = 7. ✓
Watch out. Add one more group, not six more. 6 lots = 5 lots + 1 lot.
Method. Multiplying by 2 is the same as doubling. Double the number.
- Swap the numbers round. Order does not matter in multiplication, so 9 × 2 = 2 × 9. Use the 2 times table trick.9 × 2 = 2 × 9
- Double the number. Doubling means adding the number to itself.9 + 9 = 18
- Write the answer. 9 × 2 = 18
Check. The digits of 18 add up to 9: 1 + 8 = 9. ✓
Watch out. Doubling is not adding 2. To double 7, add 7 + 7, not 7 + 2.
Method. Eight is double double double. Double the number three times.
- Double once. This gives 2 lots.6 + 6 = 12
- Double again. This gives 4 lots.double 10 = 20, double 2 = 4, so 20 + 4 = 24
- Double a third time. This gives 8 lots.double 20 = 40, double 4 = 8, so 40 + 8 = 48
- Write the answer. 8 × 6 = 48
Check. Check by dividing: 48 ÷ 6 = 8. ✓
Watch out. Count your doubles. Three doubles give 8 lots. Two doubles only give 4.
Method. Eleven is ten and one more. Multiply by 10, then add one more group.
- Multiply by 10. 10 lots of the number first.10 × 3 = 30
- Add one more group. 11 = 10 + 1, so add the number itself once more. You can also write the digit twice: 33.30 + 3 = 33
- Write the answer. 11 × 3 = 33
Check. Check by dividing: 33 ÷ 3 = 11. ✓
Watch out. The “write the digit twice” trick only works from 11 × 1 to 11 × 9. For 11 × 12 it does not give 1212. Use 10 lots + 1 lot.
Method. Five is half of ten. Multiply by 10 first, then halve the answer.
- Swap the numbers round. Order does not matter in multiplication, so 8 × 5 = 5 × 8. Use the 5 times table trick.8 × 5 = 5 × 8
- Multiply by 10. This is easy: move the digits one place to the left.10 × 8 = 80
- Halve the answer. 5 is half of 10, so 5 lots of a number is half of 10 lots.half of 80 = 40
- Write the answer. Answers in the 5 times table end in 0 or 5.8 × 5 = 40
Check. Check by dividing: 40 ÷ 5 = 8. ✓
Watch out. Halve the answer to 10 × the number. Do not halve the number before you multiply by 10 and then forget to multiply.
Method. Four is double double. Double the number, then double the answer.
- Swap the numbers round. Order does not matter in multiplication, so 9 × 4 = 4 × 9. Use the 4 times table trick.9 × 4 = 4 × 9
- Double the number. This gives 2 lots.9 + 9 = 18
- Double the answer again. Doubling twice gives 4 lots.double 10 = 20, double 8 = 16, so 20 + 16 = 36
- Write the answer. 9 × 4 = 36
Check. The digits of 36 add up to 9: 3 + 6 = 9. ✓
Watch out. You must double twice. Doubling once gives the 2 times table.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Swap the numbers round. Order does not matter in multiplication, so 4 × 10 = 10 × 4. Use the 10 times table trick.4 × 10 = 10 × 4
- Think about tens. 10 × 4 means 4 lots of 10, which is 4 tens.4 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.4 → 40
- Write the answer. 4 × 10 = 40
Check. Check by dividing: 40 ÷ 4 = 10. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. Three is double and one more. Double the number, then add the number once.
- Double the number. This gives 2 lots.3 + 3 = 6
- Add one more group. 3 = 2 + 1, so add the number once more.6 + 3 = 9
- Write the answer. 3 × 3 = 9
Check. Check by dividing: 9 ÷ 3 = 3. ✓
Watch out. Add the number itself, not 3, as the extra group.
Method. Three is double and one more. Double the number, then add the number once.
- Swap the numbers round. Order does not matter in multiplication, so 7 × 3 = 3 × 7. Use the 3 times table trick.7 × 3 = 3 × 7
- Double the number. This gives 2 lots.7 + 7 = 14
- Add one more group. 3 = 2 + 1, so add the number once more.14 + 7 = 21
- Write the answer. 7 × 3 = 21
Check. Check by dividing: 21 ÷ 3 = 7. ✓
Watch out. Add the number itself, not 3, as the extra group.
Method. Multiplying by 2 is the same as doubling. Double the number.
- Double the number. Doubling means adding the number to itself.9 + 9 = 18
- Write the answer. 2 × 9 = 18
Check. The digits of 18 add up to 9: 1 + 8 = 9. ✓
Watch out. Doubling is not adding 2. To double 7, add 7 + 7, not 7 + 2.
Method. Multiplying by 2 is the same as doubling. Double the number.
- Swap the numbers round. Order does not matter in multiplication, so 8 × 2 = 2 × 8. Use the 2 times table trick.8 × 2 = 2 × 8
- Double the number. Doubling means adding the number to itself.8 + 8 = 16
- Write the answer. 8 × 2 = 16
Check. Check by dividing: 16 ÷ 2 = 8. ✓
Watch out. Doubling is not adding 2. To double 7, add 7 + 7, not 7 + 2.
Method. Nine is one less than ten. Multiply by 10, then take away one group.
- Multiply by 10. 10 lots of the number first.10 × 6 = 60
- Take away one group. 9 = 10 − 1, so take away the number itself once.60 − 6 = 54
- Write the answer. Answers in the 9 times table have digits that add up to 9 (or 18).9 × 6 = 54
Check. The digits of 54 add up to 9: 5 + 4 = 9. ✓
Watch out. Take away 6, the other number, not 9. For 9 × 6 you work out 10 × 6 − 6.
Method. Twelve is ten and two. Multiply by 10, multiply by 2, then add.
- Multiply by 10. Move the digits one place to the left.10 × 6 = 60
- Multiply by 2. Double the number.6 + 6 = 12
- Add the two answers together. 12 = 10 + 2.60 + 12 = 72
- Write the answer. 12 × 6 = 72
Check. Check by dividing: 72 ÷ 6 = 12. ✓
Watch out. Do both parts, 10 lots and 2 lots, then add. Do not stop after 10 lots.
Method. Twelve is ten and two. Multiply by 10, multiply by 2, then add.
- Multiply by 10. Move the digits one place to the left.10 × 7 = 70
- Multiply by 2. Double the number.7 + 7 = 14
- Add the two answers together. 12 = 10 + 2.70 + 14 = 84
- Write the answer. 12 × 7 = 84
Check. Check by dividing: 84 ÷ 7 = 12. ✓
Watch out. Do both parts, 10 lots and 2 lots, then add. Do not stop after 10 lots.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Swap the numbers round. Order does not matter in multiplication, so 7 × 10 = 10 × 7. Use the 10 times table trick.7 × 10 = 10 × 7
- Think about tens. 10 × 7 means 7 lots of 10, which is 7 tens.7 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.7 → 70
- Write the answer. 7 × 10 = 70
Check. Check by dividing: 70 ÷ 7 = 10. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. Six is five and one more. Work out 5 lots, then add one more group.
- Work out 5 lots. The 5 times table is half of the 10 times table: 70 halved.5 × 7 = 35
- Add one more group. 6 = 5 + 1, so add the number once more.35 + 7 = 42
- Write the answer. 6 × 7 = 42
Check. Check by dividing: 42 ÷ 6 = 7. ✓
Watch out. Add one more group, not six more. 6 lots = 5 lots + 1 lot.
Method. Eight is double double double. Double the number three times.
- Swap the numbers round. Order does not matter in multiplication, so 6 × 8 = 8 × 6. Use the 8 times table trick.6 × 8 = 8 × 6
- Double once. This gives 2 lots.6 + 6 = 12
- Double again. This gives 4 lots.double 10 = 20, double 2 = 4, so 20 + 4 = 24
- Double a third time. This gives 8 lots.double 20 = 40, double 4 = 8, so 40 + 8 = 48
- Write the answer. 6 × 8 = 48
Check. Check by dividing: 48 ÷ 6 = 8. ✓
Watch out. Count your doubles. Three doubles give 8 lots. Two doubles only give 4.
Method. Eleven is ten and one more. Multiply by 10, then add one more group.
- Swap the numbers round. Order does not matter in multiplication, so 12 × 11 = 11 × 12. Use the 11 times table trick.12 × 11 = 11 × 12
- Multiply by 10. 10 lots of the number first.10 × 12 = 120
- Add one more group. 11 = 10 + 1, so add the number itself once more.120 + 12 = 132
- Write the answer. 12 × 11 = 132
Check. Check by dividing: 132 ÷ 11 = 12. ✓
Watch out. The “write the digit twice” trick only works from 11 × 1 to 11 × 9. For 11 × 12 it does not give 1212. Use 10 lots + 1 lot.
Method. Twelve is ten and two. Multiply by 10, multiply by 2, then add.
- Multiply by 10. Move the digits one place to the left.10 × 12 = 120
- Multiply by 2. Double the number.double 10 = 20, double 2 = 4, so 20 + 4 = 24
- Add the two answers together. 12 = 10 + 2.120 + 24 = 144
- Write the answer. 12 × 12 = 144
Check. Check by dividing: 144 ÷ 12 = 12. ✓
Watch out. Do both parts, 10 lots and 2 lots, then add. Do not stop after 10 lots.
Method. Eleven is ten and one more. Multiply by 10, then add one more group.
- Multiply by 10. 10 lots of the number first.10 × 8 = 80
- Add one more group. 11 = 10 + 1, so add the number itself once more. You can also write the digit twice: 88.80 + 8 = 88
- Write the answer. 11 × 8 = 88
Check. Check by dividing: 88 ÷ 8 = 11. ✓
Watch out. The “write the digit twice” trick only works from 11 × 1 to 11 × 9. For 11 × 12 it does not give 1212. Use 10 lots + 1 lot.
Method. To multiply by 10, every digit moves one place to the left. The ones become tens.
- Swap the numbers round. Order does not matter in multiplication, so 8 × 10 = 10 × 8. Use the 10 times table trick.8 × 10 = 10 × 8
- Think about tens. 10 × 8 means 8 lots of 10, which is 8 tens.8 tens
- Move the digits one place to the left. A tens column needs a 0 in the ones place.8 → 80
- Write the answer. 8 × 10 = 80
Check. Check by dividing: 80 ÷ 8 = 10. ✓
Watch out. The 10 times table has a 0 in the ones place every time. Put the 0 on the end, but think “tens” so you understand why.
Method. Four is double double. Double the number, then double the answer.
- Swap the numbers round. Order does not matter in multiplication, so 12 × 4 = 4 × 12. Use the 4 times table trick.12 × 4 = 4 × 12
- Double the number. This gives 2 lots.double 10 = 20, double 2 = 4, so 20 + 4 = 24
- Double the answer again. Doubling twice gives 4 lots.double 20 = 40, double 4 = 8, so 40 + 8 = 48
- Write the answer. 12 × 4 = 48
Check. Check by dividing: 48 ÷ 4 = 12. ✓
Watch out. You must double twice. Doubling once gives the 2 times table.
Method. Twelve is ten and two. Multiply by 10, multiply by 2, then add.
- Multiply by 10. Move the digits one place to the left.10 × 8 = 80
- Multiply by 2. Double the number.8 + 8 = 16
- Add the two answers together. 12 = 10 + 2.80 + 16 = 96
- Write the answer. 12 × 8 = 96
Check. Check by dividing: 96 ÷ 8 = 12. ✓
Watch out. Do both parts, 10 lots and 2 lots, then add. Do not stop after 10 lots.
Method. Eight is double double double. Double the number three times.
- Swap the numbers round. Order does not matter in multiplication, so 7 × 8 = 8 × 7. Use the 8 times table trick.7 × 8 = 8 × 7
- Double once. This gives 2 lots.7 + 7 = 14
- Double again. This gives 4 lots.double 10 = 20, double 4 = 8, so 20 + 8 = 28
- Double a third time. This gives 8 lots.double 20 = 40, double 8 = 16, so 40 + 16 = 56
- Write the answer. 7 × 8 = 56
Check. Check by dividing: 56 ÷ 7 = 8. ✓
Watch out. Count your doubles. Three doubles give 8 lots. Two doubles only give 4.
Method. Nine is one less than ten. Multiply by 10, then take away one group.
- Swap the numbers round. Order does not matter in multiplication, so 7 × 9 = 9 × 7. Use the 9 times table trick.7 × 9 = 9 × 7
- Multiply by 10. 10 lots of the number first.10 × 7 = 70
- Take away one group. 9 = 10 − 1, so take away the number itself once.70 − 7 = 63
- Write the answer. Answers in the 9 times table have digits that add up to 9 (or 18).7 × 9 = 63
Check. The digits of 63 add up to 9: 6 + 3 = 9. ✓
Watch out. Take away 7, the other number, not 9. For 9 × 7 you work out 10 × 7 − 7.
Method. Five is half of ten. Multiply by 10 first, then halve the answer.
- Swap the numbers round. Order does not matter in multiplication, so 9 × 5 = 5 × 9. Use the 5 times table trick.9 × 5 = 5 × 9
- Multiply by 10. This is easy: move the digits one place to the left.10 × 9 = 90
- Halve the answer. 5 is half of 10, so 5 lots of a number is half of 10 lots.half of 80 = 40, half of 10 = 5, so 40 + 5 = 45
- Write the answer. Answers in the 5 times table end in 0 or 5.9 × 5 = 45
Check. The digits of 45 add up to 9: 4 + 5 = 9. ✓
Watch out. Halve the answer to 10 × the number. Do not halve the number before you multiply by 10 and then forget to multiply.
Method. Multiplying by 2 is the same as doubling. Double the number.
- Double the number. Doubling means adding the number to itself.double 10 = 20, double 2 = 4, so 20 + 4 = 24
- Write the answer. 2 × 12 = 24
Check. Check by dividing: 24 ÷ 2 = 12. ✓
Watch out. Doubling is not adding 2. To double 7, add 7 + 7, not 7 + 2.
Method. Nine is one less than ten. Multiply by 10, then take away one group.
- Swap the numbers round. Order does not matter in multiplication, so 12 × 9 = 9 × 12. Use the 9 times table trick.12 × 9 = 9 × 12
- Multiply by 10. 10 lots of the number first.10 × 12 = 120
- Take away one group. 9 = 10 − 1, so take away the number itself once.120 − 12 = 108
- Write the answer. Answers in the 9 times table have digits that add up to 9 (or 18).12 × 9 = 108
Check. Check by dividing: 108 ÷ 9 = 12. ✓
Watch out. Take away 12, the other number, not 9. For 9 × 12 you work out 10 × 12 − 12.
Method. Five is half of ten. Multiply by 10 first, then halve the answer.
- Swap the numbers round. Order does not matter in multiplication, so 6 × 5 = 5 × 6. Use the 5 times table trick.6 × 5 = 5 × 6
- Multiply by 10. This is easy: move the digits one place to the left.10 × 6 = 60
- Halve the answer. 5 is half of 10, so 5 lots of a number is half of 10 lots.half of 60 = 30
- Write the answer. Answers in the 5 times table end in 0 or 5.6 × 5 = 30
Check. Check by dividing: 30 ÷ 5 = 6. ✓
Watch out. Halve the answer to 10 × the number. Do not halve the number before you multiply by 10 and then forget to multiply.
Method. Four is double double. Double the number, then double the answer.
- Double the number. This gives 2 lots.9 + 9 = 18
- Double the answer again. Doubling twice gives 4 lots.double 10 = 20, double 8 = 16, so 20 + 16 = 36
- Write the answer. 4 × 9 = 36
Check. The digits of 36 add up to 9: 3 + 6 = 9. ✓
Watch out. You must double twice. Doubling once gives the 2 times table.
Method. Six is five and one more. Work out 5 lots, then add one more group.
- Work out 5 lots. The 5 times table is half of the 10 times table: 60 halved.5 × 6 = 30
- Add one more group. 6 = 5 + 1, so add the number once more.30 + 6 = 36
- Write the answer. 6 × 6 = 36
Check. Check by dividing: 36 ÷ 6 = 6. ✓
Watch out. Add one more group, not six more. 6 lots = 5 lots + 1 lot.
Method. Nine is one less than ten. Multiply by 10, then take away one group.
- Multiply by 10. 10 lots of the number first.10 × 3 = 30
- Take away one group. 9 = 10 − 1, so take away the number itself once.30 − 3 = 27
- Write the answer. Answers in the 9 times table have digits that add up to 9 (or 18).9 × 3 = 27
Check. The digits of 27 add up to 9: 2 + 7 = 9. ✓
Watch out. Take away 3, the other number, not 9. For 9 × 3 you work out 10 × 3 − 3.
Method. Five is half of ten. Multiply by 10 first, then halve the answer.
- Multiply by 10. This is easy: move the digits one place to the left.10 × 7 = 70
- Halve the answer. 5 is half of 10, so 5 lots of a number is half of 10 lots.half of 60 = 30, half of 10 = 5, so 30 + 5 = 35
- Write the answer. Answers in the 5 times table end in 0 or 5.5 × 7 = 35
Check. Check by dividing: 35 ÷ 5 = 7. ✓
Watch out. Halve the answer to 10 × the number. Do not halve the number before you multiply by 10 and then forget to multiply.
Method. Use the 7 times table. Count up in 7s until you reach 56.
- Turn the division into a missing multiplication. 56 ÷ 7 asks: what do we multiply 7 by to get 56?56 ÷ 7 = ? means ? × 7 = 56
- Count up in 7s until you reach 56. Each number you say is one more group of 7.7, 14, 21, 28, 35, 42, 49, 56
- Count how many numbers you said. The number of jumps is the answer.I said 8 numbers, so 8 × 7 = 56
- Write the answer. 56 ÷ 7 = 8
Check. Multiply back: 8 × 7 = 56. ✓
Watch out. Know your 7 times table facts, then division is quick.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. We need the number that 6 is multiplied by to make 36.6 × ? = 36
- Use the inverse (opposite) operation. The opposite of multiplying is dividing. Divide 36 by 6.36 ÷ 6 = 6
- Write the missing number. 6 × 6 = 36
Check. Put it back: 6 × 6 = 36. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. We need the number that, multiplied by 6, makes 24.? × 6 = 24
- Use the inverse (opposite) operation. Order does not matter in multiplication. Divide 24 by 6.24 ÷ 6 = 4
- Write the missing number. 4 × 6 = 24
Check. Put it back: 4 × 6 = 24. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. A number divided by 7 gives 10.? ÷ 7 = 10
- Use the inverse (opposite) operation. The opposite of dividing by 7 is multiplying by 7.10 × 7 = 70
- Write the missing number. 70 ÷ 7 = 10
Check. Put it back: 70 ÷ 7 = 10. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. 132 divided by the missing number makes 12.132 ÷ ? = 12
- Turn it into a multiplication. 12 lots of the missing number make 132.12 × ? = 132, so ? = 132 ÷ 12
- Work out the division. Count up in 12s, or use the 12 times table.132 ÷ 12 = 11
- Write the missing number. 132 ÷ 11 = 12
Check. Put it back: 132 ÷ 11 = 12. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Method. Use the 6 times table. Count up in 6s until you reach 30.
- Turn the division into a missing multiplication. 30 ÷ 6 asks: what do we multiply 6 by to get 30?30 ÷ 6 = ? means ? × 6 = 30
- Count up in 6s until you reach 30. Each number you say is one more group of 6.6, 12, 18, 24, 30
- Count how many numbers you said. The number of jumps is the answer.I said 5 numbers, so 5 × 6 = 30
- Write the answer. 30 ÷ 6 = 5
Check. Multiply back: 5 × 6 = 30. ✓
Watch out. Know your 6 times table facts, then division is quick.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. We need the number that 11 is multiplied by to make 121.11 × ? = 121
- Use the inverse (opposite) operation. The opposite of multiplying is dividing. Divide 121 by 11.121 ÷ 11 = 11
- Write the missing number. 11 × 11 = 121
Check. Put it back: 11 × 11 = 121. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. We need the number that, multiplied by 3, makes 21.? × 3 = 21
- Use the inverse (opposite) operation. Order does not matter in multiplication. Divide 21 by 3.21 ÷ 3 = 7
- Write the missing number. 7 × 3 = 21
Check. Put it back: 7 × 3 = 21. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. A number divided by 3 gives 10.? ÷ 3 = 10
- Use the inverse (opposite) operation. The opposite of dividing by 3 is multiplying by 3.10 × 3 = 30
- Write the missing number. 30 ÷ 3 = 10
Check. Put it back: 30 ÷ 3 = 10. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. 30 divided by the missing number makes 6.30 ÷ ? = 6
- Turn it into a multiplication. 6 lots of the missing number make 30.6 × ? = 30, so ? = 30 ÷ 6
- Work out the division. Count up in 6s, or use the 6 times table.30 ÷ 6 = 5
- Write the missing number. 30 ÷ 5 = 6
Check. Put it back: 30 ÷ 5 = 6. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Method. Use the 11 times table. Count up in 11s until you reach 99.
- Turn the division into a missing multiplication. 99 ÷ 11 asks: what do we multiply 11 by to get 99?99 ÷ 11 = ? means ? × 11 = 99
- Count up in 11s until you reach 99. Each number you say is one more group of 11.11, 22, 33, 44, 55, 66, 77, 88, 99
- Count how many numbers you said. The number of jumps is the answer.I said 9 numbers, so 9 × 11 = 99
- Write the answer. 99 ÷ 11 = 9
Check. Multiply back: 9 × 11 = 99. ✓
Watch out. Know your 11 times table facts, then division is quick.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. We need the number that 5 is multiplied by to make 40.5 × ? = 40
- Use the inverse (opposite) operation. The opposite of multiplying is dividing. Divide 40 by 5.40 ÷ 5 = 8
- Write the missing number. 5 × 8 = 40
Check. Put it back: 5 × 8 = 40. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. We need the number that, multiplied by 8, makes 32.? × 8 = 32
- Use the inverse (opposite) operation. Order does not matter in multiplication. Divide 32 by 8.32 ÷ 8 = 4
- Write the missing number. 4 × 8 = 32
Check. Put it back: 4 × 8 = 32. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. A number divided by 4 gives 11.? ÷ 4 = 11
- Use the inverse (opposite) operation. The opposite of dividing by 4 is multiplying by 4.11 × 4 = 44
- Write the missing number. 44 ÷ 4 = 11
Check. Put it back: 44 ÷ 4 = 11. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. 77 divided by the missing number makes 11.77 ÷ ? = 11
- Turn it into a multiplication. 11 lots of the missing number make 77.11 × ? = 77, so ? = 77 ÷ 11
- Work out the division. Count up in 11s, or use the 11 times table.77 ÷ 11 = 7
- Write the missing number. 77 ÷ 7 = 11
Check. Put it back: 77 ÷ 7 = 11. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Method. To divide by 10, every digit moves one place to the right.
- Turn the division into a missing multiplication. 60 ÷ 10 asks: what do we multiply 10 by to get 60?60 ÷ 10 = ? means ? × 10 = 60
- Move the digits one place to the right. Tens become ones.60 → 6
- Write the answer. 60 ÷ 10 = 6
Check. Multiply back: 6 × 10 = 60. ✓
Watch out. Check that the number gets smaller. Dividing by 10 makes ten times smaller.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. We need the number that 6 is multiplied by to make 36.6 × ? = 36
- Use the inverse (opposite) operation. The opposite of multiplying is dividing. Divide 36 by 6.36 ÷ 6 = 6
- Write the missing number. 6 × 6 = 36
Check. Put it back: 6 × 6 = 36. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. We need the number that, multiplied by 4, makes 16.? × 4 = 16
- Use the inverse (opposite) operation. Order does not matter in multiplication. Divide 16 by 4.16 ÷ 4 = 4
- Write the missing number. 4 × 4 = 16
Check. Put it back: 4 × 4 = 16. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. A number divided by 6 gives 11.? ÷ 6 = 11
- Use the inverse (opposite) operation. The opposite of dividing by 6 is multiplying by 6.11 × 6 = 66
- Write the missing number. 66 ÷ 6 = 11
Check. Put it back: 66 ÷ 6 = 11. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Key words. A missing number is a number you have to find. Division and multiplication are inverses (opposites): they undo each other.
Method. Use the inverse operation. Multiplication and division undo each other.
- Say what the sentence means. 120 divided by the missing number makes 12.120 ÷ ? = 12
- Turn it into a multiplication. 12 lots of the missing number make 120.12 × ? = 120, so ? = 120 ÷ 12
- Work out the division. Count up in 12s, or use the 12 times table.120 ÷ 12 = 10
- Write the missing number. 120 ÷ 10 = 12
Check. Put it back: 120 ÷ 10 = 12. ✓
Watch out. Do not just put the numbers in the box in the order you see them. Think about what the sentence means.
Method. There are 25 questions and 6 seconds for each. Multiply, then change the seconds into minutes and seconds.
- Multiply 25 by 6. Split 25 into 20 and 5.20 × 6 = 120 and 5 × 6 = 30, so 120 + 30 = 150 seconds
- Change to minutes and seconds. 1 minute is 60 seconds. 2 minutes is 120 seconds.150 = 120 + 30, so 150 seconds = 2 minutes 30 seconds
- Write the answer. 150 seconds = 2 minutes 30 seconds
Check. 2 minutes 30 seconds = 120 + 30 = 150 seconds. 150 ÷ 6 = 25. ✓
Watch out. There is a short rest between questions in the real check, but the 6 seconds is for answering each question.
Method. There is more than one trick for each fact. Pick two that you trust.
- Way 1: double three times. The 8 times table is double, double, double.double 7 = 14, double 14 = 28, double 28 = 56
- Way 2: use 5 lots and 2 lots. 7 = 5 + 2, so 7 lots of 8 is 5 lots of 8 plus 2 lots of 8.5 × 8 = 40 and 2 × 8 = 16, so 40 + 16 = 56
- Write the answer. Both ways give the same answer.7 × 8 = 56
Check. Also 56 ÷ 7 = 8. ✓
Watch out. A third way: 7 × 7 = 49, and 49 + 7 = 56.
Method. Look for facts that are repeated in the grid because of commutativity.
- Look at the grid. The grid is a mirror image across the diagonal (6, 49, 64, 81 and so on).For example 6 × 7 and 7 × 6 are both 42.
- Count the different facts. The 4 square facts (6 × 6, 7 × 7, 8 × 8, 9 × 9) are on the diagonal. The other 12 boxes make 6 pairs of repeats.4 + 6 = 10
- List them. 6 × 6, 6 × 7, 6 × 8, 6 × 9, 7 × 7, 7 × 8, 7 × 9, 8 × 8, 8 × 9, 9 × 9
- Answer Dev. Only 10 facts are different.
Check. 4 squares + 12 other boxes ÷ 2 = 4 + 6 = 10. ✓
Watch out. Learn both orders in your head: when you see 8 × 6, think 6 × 8.