Adding and taking away within 10
By the end of this chapter you will be able to
- Use one bond to write an addition fact and a subtraction fact
- Use a family of three numbers to check sums
- Find the missing number in a sum
- Solve one-step stories about adding or taking away
You should already know
- Adding within 10 (Chapter 6)
- Taking away within 10 (Chapter 7)
- Number bonds to 10 (Chapter 5)
Where this leads
- Number stories within 20 (Level 1, Chapter 9)
Step-by-step practice: maths (Level 1). Small steps, repeated until fluent. Content: Use a number bond to help with addition and with subtraction, See that addition and subtraction are linked, using fact families of three numbers, Find a missing number in a sum such as 4 + ? = 9 or 9 - ? = 4, Solve one-step word problems about adding or taking away, up to 10.
Exercise P Do you remember?
Non-calculatorMethod. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.4
- Count on 3 more. We add 3 to 4.4 + 3
- Write the answer. 7
Check. Count on from the other number too. You get 7 both ways.
Watch out. Count on, do not start again from one.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.8
- Take away 5. Cross out or count back this many.8 - 5
- Write the answer. This is how many are left.3
Check. Add back: 3 + 5 = 8. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 10 and the known part is 6.10 and 6
- Count on from the known part to the whole. Or take the known part away from the whole.10 - 6 = 4
- Write the missing part. 4
Check. Put the two parts back together: 6 and 4 make 10.
Watch out. The two parts always add up to the whole.
Method. Start at 9 and count back four jumps.
- Start at 9. This is where we begin.9
- Count back 4. Eight, seven, six, five.8, 7, 6, 5
- Write the answer. 5
Check. Count on 4 from 5: 6, 7, 8, 9. It works.
Watch out. Count back, to the left.
Method. More means add.
- Start with 2 balls. Tom had two balls.2
- Add the 5 more. Five more came.2 + 5 = 7
- Write the answer. 7
Check. Count on 5 from 2: 3, 4, 5, 6, 7. It works.
Watch out. More means add.
One bond, two kinds of sum
One number bond gives you two addition facts and two subtraction facts.
Look at the bond. The whole is at the top. Add the two parts to make the whole. Take a part away from the whole to get the other part.
Key ideas
- A bond has two parts and a whole.
- Adding the parts makes the whole.
- Taking a part away from the whole gives the other part.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 9 and one part is 4.9 and 4
- Take the part away. What is left is the other part.9 - 4 = 5
- Write the answer. 5
Check. Add back: 5 + 4 = 9. It works.
Watch out. The bond gives you a subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.7
- Count on 2 more. We add 2 to 7.7 + 2
- Write the answer. 9
Check. Count on from the other number too. You get 9 both ways.
Watch out. Count on, do not start again from one.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.7
- Take away 3. Cross out or count back this many.7 - 3
- Write the answer. This is how many are left.4
Check. Add back: 4 + 3 = 7. The answer is right.
Watch out. Count back from the first number, not up from the second.
Watch out
Watch out. Take away the part you know from the whole, not the other way round.
Exam tip
Grown-up tip. Draw a bond with two cups and one big cup. Put counters in the small cups, then ask your child to find the total and the missing part.
Exercise 8A One bond, two kinds of sum
Non-calculatorMethod. Take the part you know away from the whole.
- Read the bond. The whole is 8 and one part is 6.8 and 6
- Take the part away. What is left is the other part.8 - 6 = 2
- Write the answer. 2
Check. Add back: 2 + 6 = 8. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.4
- Count on 3 more. We add 3 to 4.4 + 3
- Write the answer. 7
Check. Count on from the other number too. You get 7 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 9 and one part is 8.9 and 8
- Take the part away. What is left is the other part.9 - 8 = 1
- Write the answer. 1
Check. Add back: 1 + 8 = 9. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.3
- Count on 3 more. We add 3 to 3.3 + 3
- Write the answer. 6
Check. Count on from the other number too. You get 6 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 5 and one part is 4.5 and 4
- Take the part away. What is left is the other part.5 - 4 = 1
- Write the answer. 1
Check. Add back: 1 + 4 = 5. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.5
- Count on 3 more. We add 3 to 5.5 + 3
- Write the answer. 8
Check. Count on from the other number too. You get 8 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 10 and one part is 1.10 and 1
- Take the part away. What is left is the other part.10 - 1 = 9
- Write the answer. 9
Check. Add back: 9 + 1 = 10. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.6
- Count on 4 more. We add 4 to 6.6 + 4
- Write the answer. 10
Check. Count on from the other number too. You get 10 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 7 and one part is 3.7 and 3
- Take the part away. What is left is the other part.7 - 3 = 4
- Write the answer. 4
Check. Add back: 4 + 3 = 7. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.7
- Count on 3 more. We add 3 to 7.7 + 3
- Write the answer. 10
Check. Count on from the other number too. You get 10 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 8 and one part is 7.8 and 7
- Take the part away. What is left is the other part.8 - 7 = 1
- Write the answer. 1
Check. Add back: 1 + 7 = 8. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.8
- Count on 2 more. We add 2 to 8.8 + 2
- Write the answer. 10
Check. Count on from the other number too. You get 10 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 3 and one part is 2.3 and 2
- Take the part away. What is left is the other part.3 - 2 = 1
- Write the answer. 1
Check. Add back: 1 + 2 = 3. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.8
- Count on 1 more. We add 1 to 8.8 + 1
- Write the answer. 9
Check. Count on from the other number too. You get 9 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 10 and one part is 2.10 and 2
- Take the part away. What is left is the other part.10 - 2 = 8
- Write the answer. 8
Check. Add back: 8 + 2 = 10. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.9
- Count on 1 more. We add 1 to 9.9 + 1
- Write the answer. 10
Check. Count on from the other number too. You get 10 both ways.
Watch out. Count on, do not start again from one.
Fact families of three numbers
Three numbers can make a fact family. For example, 3, 6 and 9 make these facts:
3 + 6 = 9, 6 + 3 = 9, 9 − 6 = 3 and 9 − 3 = 6.
Key ideas
- Swapping the two parts does not change the total.
- Subtraction undoes addition.
- One family gives four facts.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.6
- Take away 2. Cross out or count back this many.6 - 2
- Write the answer. This is how many are left.4
Check. Add back: 4 + 2 = 6. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.5
- Count on 3 more. We add 3 to 5.5 + 3
- Write the answer. 8
Check. Count on from the other number too. You get 8 both ways.
Watch out. Count on, do not start again from one.
Method. The fact family gives a subtraction fact.
- Read the addition. 2 + 7 = 9.2 + 7 = 9
- Take one part away from the total. Take away 2 from 9.9 - 2 = 7
- Write the answer. 7
Check. Add back: 7 + 2 = 9. It works.
Watch out. The subtraction takes away the part that was added.
Watch out
Watch out. You cannot swap the numbers in a subtraction: 9 − 2 is not the same as 2 − 9.
Exam tip
Grown-up tip. Write one family on a card. Ask your child to say the four facts out loud, then cover one number and ask which number is hidden.
Exercise 8B Fact families
Non-calculatorMethod. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.4
- Count on 1 more. We add 1 to 4.4 + 1
- Write the answer. 5
Check. Count on from the other number too. You get 5 both ways.
Watch out. Count on, do not start again from one.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.8
- Take away 3. Cross out or count back this many.8 - 3
- Write the answer. This is how many are left.5
Check. Add back: 5 + 3 = 8. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.10
- Take away 4. Cross out or count back this many.10 - 4
- Write the answer. This is how many are left.6
Check. Add back: 6 + 4 = 10. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Use the same three numbers in both facts.
- Read the addition. 9 + 1 = 10.9 + 1 = 10
- Take the second part away from the total. This gives the first part.10 - 1 = 9
- Write the answer. 9
Check. Add back: 9 + 1 = 10. ✓
Watch out. The same three numbers make a family of facts.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.5
- Count on 4 more. We add 4 to 5.5 + 4
- Write the answer. 9
Check. Count on from the other number too. You get 9 both ways.
Watch out. Count on, do not start again from one.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.8
- Take away 7. Cross out or count back this many.8 - 7
- Write the answer. This is how many are left.1
Check. Add back: 1 + 7 = 8. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.10
- Take away 7. Cross out or count back this many.10 - 7
- Write the answer. This is how many are left.3
Check. Add back: 3 + 7 = 10. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Use the same three numbers in both facts.
- Read the addition. 4 + 5 = 9.4 + 5 = 9
- Take the second part away from the total. This gives the first part.9 - 5 = 4
- Write the answer. 4
Check. Add back: 4 + 5 = 9. ✓
Watch out. The same three numbers make a family of facts.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.5
- Count on 5 more. We add 5 to 5.5 + 5
- Write the answer. 10
Check. Count on from the other number too. You get 10 both ways.
Watch out. Count on, do not start again from one.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.8
- Take away 1. Cross out or count back this many.8 - 1
- Write the answer. This is how many are left.7
Check. Add back: 7 + 1 = 8. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.7
- Take away 3. Cross out or count back this many.7 - 3
- Write the answer. This is how many are left.4
Check. Add back: 4 + 3 = 7. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Use the same three numbers in both facts.
- Read the addition. 3 + 3 = 6.3 + 3 = 6
- Take the second part away from the total. This gives the first part.6 - 3 = 3
- Write the answer. 3
Check. Add back: 3 + 3 = 6. ✓
Watch out. The same three numbers make a family of facts.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.4
- Count on 4 more. We add 4 to 4.4 + 4
- Write the answer. 8
Check. Count on from the other number too. You get 8 both ways.
Watch out. Count on, do not start again from one.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.10
- Take away 1. Cross out or count back this many.10 - 1
- Write the answer. This is how many are left.9
Check. Add back: 9 + 1 = 10. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.9
- Take away 6. Cross out or count back this many.9 - 6
- Write the answer. This is how many are left.3
Check. Add back: 3 + 6 = 9. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Use the same three numbers in both facts.
- Read the addition. 2 + 4 = 6.2 + 4 = 6
- Take the second part away from the total. This gives the first part.6 - 4 = 2
- Write the answer. 2
Check. Add back: 2 + 4 = 6. ✓
Watch out. The same three numbers make a family of facts.
Finding the missing number
Some sums have a box. The box is a missing number.
For a sum with a box, ask: “What do I need to make it right?”
Key ideas
- A box is a missing number.
- For + sums, count on from the known part to the total.
- For − sums, add back the number taken away.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 9 and the known part is 4.9 and 4
- Count on from the known part to the whole. Or take the known part away from the whole.9 - 4 = 5
- Write the missing part. 5
Check. Put the two parts back together: 4 and 5 make 9.
Watch out. The two parts always add up to the whole.
Method. Ask: what take away gives 6? Add back to find the start.
- Read the sum. Ten take away the box is 6.10 - ? = 6
- Add back the answer to the start. Count on from 6 to 10.6 + 4 = 10
- Write the missing number. 4
Check. 10 - 4 = 6. It works.
Watch out. The box is the number taken away.
Method. The box is the start number. Add back the 3.
- Read the sum. The box take away 3 is 4.? - 3 = 4
- Add back the 3. Count on 3 from 4 to find the start.4 + 3 = 7
- Write the missing number. 7
Check. 7 - 3 = 4. It works.
Watch out. Add back to find the start number.
Watch out
Watch out. Do not just write the number you see. Ask what the box must be to make the sum right.
Exam tip
Grown-up tip. Cover one number in a sum with your hand. Ask: “What number was hidden?” Check by reading the whole sum again.
Exercise 8C Finding the missing number
Non-calculatorMethod. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 6 and the known part is 5.6 and 5
- Count on from the known part to the whole. Or take the known part away from the whole.6 - 5 = 1
- Write the missing part. 1
Check. Put the two parts back together: 5 and 1 make 6.
Watch out. The two parts always add up to the whole.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 4 and the known part is 1.4 and 1
- Count on from the known part to the whole. Or take the known part away from the whole.4 - 1 = 3
- Write the missing part. 3
Check. Put the two parts back together: 1 and 3 make 4.
Watch out. The two parts always add up to the whole.
Method. Ask: what take away gives this answer? Count on from the answer to the start.
- Read the sum. 9 take away the box is 6.9 - ? = 6
- Count on from the answer to the start. Adding back the box gives the start.6 + ? = 9
- Write the missing number. 3
Check. 9 - 3 = 6. ✓
Watch out. When the box is taken away, count on from the answer to the start.
Method. The box is the start number. Add back the number taken away.
- Read the sum. The box take away 3 is 1.? - 3 = 1
- Add back the number taken away. Count on from the answer to find the start.1 + 3 = 4
- Write the missing number. 4
Check. 4 - 3 = 1. ✓
Watch out. Add back to find the start number.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 7 and the known part is 6.7 and 6
- Count on from the known part to the whole. Or take the known part away from the whole.7 - 6 = 1
- Write the missing part. 1
Check. Put the two parts back together: 6 and 1 make 7.
Watch out. The two parts always add up to the whole.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 9 and the known part is 6.9 and 6
- Count on from the known part to the whole. Or take the known part away from the whole.9 - 6 = 3
- Write the missing part. 3
Check. Put the two parts back together: 6 and 3 make 9.
Watch out. The two parts always add up to the whole.
Method. Ask: what take away gives this answer? Count on from the answer to the start.
- Read the sum. 10 take away the box is 8.10 - ? = 8
- Count on from the answer to the start. Adding back the box gives the start.8 + ? = 10
- Write the missing number. 2
Check. 10 - 2 = 8. ✓
Watch out. When the box is taken away, count on from the answer to the start.
Method. The box is the start number. Add back the number taken away.
- Read the sum. The box take away 3 is 7.? - 3 = 7
- Add back the number taken away. Count on from the answer to find the start.7 + 3 = 10
- Write the missing number. 10
Check. 10 - 3 = 7. ✓
Watch out. Add back to find the start number.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 8 and the known part is 1.8 and 1
- Count on from the known part to the whole. Or take the known part away from the whole.8 - 1 = 7
- Write the missing part. 7
Check. Put the two parts back together: 1 and 7 make 8.
Watch out. The two parts always add up to the whole.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 10 and the known part is 2.10 and 2
- Count on from the known part to the whole. Or take the known part away from the whole.10 - 2 = 8
- Write the missing part. 8
Check. Put the two parts back together: 2 and 8 make 10.
Watch out. The two parts always add up to the whole.
Method. Ask: what take away gives this answer? Count on from the answer to the start.
- Read the sum. 6 take away the box is 2.6 - ? = 2
- Count on from the answer to the start. Adding back the box gives the start.2 + ? = 6
- Write the missing number. 4
Check. 6 - 4 = 2. ✓
Watch out. When the box is taken away, count on from the answer to the start.
Method. The box is the start number. Add back the number taken away.
- Read the sum. The box take away 3 is 2.? - 3 = 2
- Add back the number taken away. Count on from the answer to find the start.2 + 3 = 5
- Write the missing number. 5
Check. 5 - 3 = 2. ✓
Watch out. Add back to find the start number.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 3 and the known part is 2.3 and 2
- Count on from the known part to the whole. Or take the known part away from the whole.3 - 2 = 1
- Write the missing part. 1
Check. Put the two parts back together: 2 and 1 make 3.
Watch out. The two parts always add up to the whole.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 5 and the known part is 1.5 and 1
- Count on from the known part to the whole. Or take the known part away from the whole.5 - 1 = 4
- Write the missing part. 4
Check. Put the two parts back together: 1 and 4 make 5.
Watch out. The two parts always add up to the whole.
Method. Ask: what take away gives this answer? Count on from the answer to the start.
- Read the sum. 6 take away the box is 4.6 - ? = 4
- Count on from the answer to the start. Adding back the box gives the start.4 + ? = 6
- Write the missing number. 2
Check. 6 - 2 = 4. ✓
Watch out. When the box is taken away, count on from the answer to the start.
Method. The box is the start number. Add back the number taken away.
- Read the sum. The box take away 7 is 3.? - 7 = 3
- Add back the number taken away. Count on from the answer to find the start.3 + 7 = 10
- Write the missing number. 10
Check. 10 - 7 = 3. ✓
Watch out. Add back to find the start number.
One-step stories: add or take away
Read the story slowly. Look for words like more, gets or came (add), and went, given away or eaten (take away).
Then write the sum that matches the story.
Key ideas
- More and gets mean add.
- Went and given away mean take away.
- Check that the answer makes sense.
Method. More means add.
- Start with 3 books. Zainab had three books.3
- Add the 4 more. Four more were borrowed.3 + 4 = 7
- Write the answer. 7
Check. Count on 4 from 3: 4, 5, 6, 7. It works.
Watch out. More means add.
Method. Lost means take away.
- Start with 9 marbles. Noah had nine marbles.9
- Take away the 4 lost. Four went, so take them away.9 - 4 = 5
- Write the answer. 5
Check. Add back: 5 + 4 = 9. It works.
Watch out. Lost means take away, so the answer is smaller.
Method. Gives her more means add.
- Start with 5 stickers. Mei had five stickers.5
- Add the 2 more. Two more were given.5 + 2 = 7
- Write the answer. 7
Check. Count on 2 from 5: 6, 7. It works.
Watch out. Read the whole story before you choose add or take away.
Watch out
Watch out. Some stories say “more” but mean take away. Read the whole story to find out.
Exam tip
Grown-up tip. Act out the story with objects. Ask: “Did the number go up or down?” before you ask for the answer.
Exercise 8D One-step stories
Non-calculatorMethod. Adding means we get more. Start with what there was and add the new ones.
- Start with the number at the start. Amira had 2 pencils.2
- Add the new ones. 8 more came, so we add them.2 + 8 = 10
- Write the answer. 10
Check. Count on 8 from 2: you reach 10. ✓
Watch out. More means add. Less means take away.
Method. Taking away means we get fewer. Start with the number at the start, then take away.
- Start with the number at the start. Noah had 7 stickers.7
- Take away the ones that went. 2 went, so we take them away.7 - 2 = 5
- Write the answer. 5
Check. Add back: 5 + 2 = 7. ✓
Watch out. Less means take away. Check your answer makes sense.
Method. Adding means we get more. Start with what there was and add the new ones.
- Start with the number at the start. Priya had 3 marbles.3
- Add the new ones. 2 more came, so we add them.3 + 2 = 5
- Write the answer. 5
Check. Count on 2 from 3: you reach 5. ✓
Watch out. More means add. Less means take away.
Method. Taking away means we get fewer. Start with the number at the start, then take away.
- Start with the number at the start. Jack had 6 sweets.6
- Take away the ones that went. 5 went, so we take them away.6 - 5 = 1
- Write the answer. 1
Check. Add back: 1 + 5 = 6. ✓
Watch out. Less means take away. Check your answer makes sense.
Method. Adding means we get more. Start with what there was and add the new ones.
- Start with the number at the start. Zainab had 3 books.3
- Add the new ones. 4 more came, so we add them.3 + 4 = 7
- Write the answer. 7
Check. Count on 4 from 3: you reach 7. ✓
Watch out. More means add. Less means take away.
Method. Taking away means we get fewer. Start with the number at the start, then take away.
- Start with the number at the start. Leo had 10 pencils.10
- Take away the ones that went. 8 went, so we take them away.10 - 8 = 2
- Write the answer. 2
Check. Add back: 2 + 8 = 10. ✓
Watch out. Less means take away. Check your answer makes sense.
Method. Adding means we get more. Start with what there was and add the new ones.
- Start with the number at the start. Mei had 4 stickers.4
- Add the new ones. 4 more came, so we add them.4 + 4 = 8
- Write the answer. 8
Check. Count on 4 from 4: you reach 8. ✓
Watch out. More means add. Less means take away.
Method. Taking away means we get fewer. Start with the number at the start, then take away.
- Start with the number at the start. Tom had 3 marbles.3
- Take away the ones that went. 2 went, so we take them away.3 - 2 = 1
- Write the answer. 1
Check. Add back: 1 + 2 = 3. ✓
Watch out. Less means take away. Check your answer makes sense.
Method. Adding means we get more. Start with what there was and add the new ones.
- Start with the number at the start. Aisha had 6 sweets.6
- Add the new ones. 2 more came, so we add them.6 + 2 = 8
- Write the answer. 8
Check. Count on 2 from 6: you reach 8. ✓
Watch out. More means add. Less means take away.
Method. Taking away means we get fewer. Start with the number at the start, then take away.
- Start with the number at the start. Ruby had 7 books.7
- Take away the ones that went. 5 went, so we take them away.7 - 5 = 2
- Write the answer. 2
Check. Add back: 2 + 5 = 7. ✓
Watch out. Less means take away. Check your answer makes sense.
Method. Adding means we get more. Start with what there was and add the new ones.
- Start with the number at the start. Amira had 3 pencils.3
- Add the new ones. 7 more came, so we add them.3 + 7 = 10
- Write the answer. 10
Check. Count on 7 from 3: you reach 10. ✓
Watch out. More means add. Less means take away.
Method. Taking away means we get fewer. Start with the number at the start, then take away.
- Start with the number at the start. Noah had 3 stickers.3
- Take away the ones that went. 2 went, so we take them away.3 - 2 = 1
- Write the answer. 1
Check. Add back: 1 + 2 = 3. ✓
Watch out. Less means take away. Check your answer makes sense.
Method. Adding means we get more. Start with what there was and add the new ones.
- Start with the number at the start. Priya had 2 marbles.2
- Add the new ones. 8 more came, so we add them.2 + 8 = 10
- Write the answer. 10
Check. Count on 8 from 2: you reach 10. ✓
Watch out. More means add. Less means take away.
Method. Taking away means we get fewer. Start with the number at the start, then take away.
- Start with the number at the start. Jack had 10 sweets.10
- Take away the ones that went. 2 went, so we take them away.10 - 2 = 8
- Write the answer. 8
Check. Add back: 8 + 2 = 10. ✓
Watch out. Less means take away. Check your answer makes sense.
Method. Adding means we get more. Start with what there was and add the new ones.
- Start with the number at the start. Zainab had 6 books.6
- Add the new ones. 2 more came, so we add them.6 + 2 = 8
- Write the answer. 8
Check. Count on 2 from 6: you reach 8. ✓
Watch out. More means add. Less means take away.
Method. Taking away means we get fewer. Start with the number at the start, then take away.
- Start with the number at the start. Leo had 7 pencils.7
- Take away the ones that went. 5 went, so we take them away.7 - 5 = 2
- Write the answer. 2
Check. Add back: 2 + 5 = 7. ✓
Watch out. Less means take away. Check your answer makes sense.
Chapter summary
| Skill | Method |
|---|---|
| One bond, two sums | Add the parts to make the whole. Take a part away to get the other part |
| Fact families | Three numbers make four facts. Swapping parts does not change the total |
| Missing numbers | Count on from the known part, or add back the number taken away |
| Stories | More means add. Went or lost means take away |
Can you…?
- I can use a bond to write an addition and a subtraction fact
- I can use a fact family of three numbers
- I can find the missing number in a sum
- I can solve a one-step story about adding or taking away
Key terms
- fact family
- the addition and subtraction facts made from the same three numbers
- missing number
- the number that goes in a box to make a sum right
- add back
- to add the number that was taken away, to find the start
Exercise 8Z Check-up
Non-calculatorMethod. Take the part you know away from the whole.
- Read the bond. The whole is 10 and one part is 9.10 and 9
- Take the part away. What is left is the other part.10 - 9 = 1
- Write the answer. 1
Check. Add back: 1 + 9 = 10. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.7
- Count on 1 more. We add 1 to 7.7 + 1
- Write the answer. 8
Check. Count on from the other number too. You get 8 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 3 and one part is 1.3 and 1
- Take the part away. What is left is the other part.3 - 1 = 2
- Write the answer. 2
Check. Add back: 2 + 1 = 3. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.5
- Count on 3 more. We add 3 to 5.5 + 3
- Write the answer. 8
Check. Count on from the other number too. You get 8 both ways.
Watch out. Count on, do not start again from one.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.6
- Take away 2. Cross out or count back this many.6 - 2
- Write the answer. This is how many are left.4
Check. Add back: 4 + 2 = 6. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.4
- Take away 3. Cross out or count back this many.4 - 3
- Write the answer. This is how many are left.1
Check. Add back: 1 + 3 = 4. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 8 and the known part is 6.8 and 6
- Count on from the known part to the whole. Or take the known part away from the whole.8 - 6 = 2
- Write the missing part. 2
Check. Put the two parts back together: 6 and 2 make 8.
Watch out. The two parts always add up to the whole.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 8 and the known part is 5.8 and 5
- Count on from the known part to the whole. Or take the known part away from the whole.8 - 5 = 3
- Write the missing part. 3
Check. Put the two parts back together: 5 and 3 make 8.
Watch out. The two parts always add up to the whole.
Method. Adding means we get more. Start with what there was and add the new ones.
- Start with the number at the start. Amira had 2 pencils.2
- Add the new ones. 3 more came, so we add them.2 + 3 = 5
- Write the answer. 5
Check. Count on 3 from 2: you reach 5. ✓
Watch out. More means add. Less means take away.
Method. Taking away means we get fewer. Start with the number at the start, then take away.
- Start with the number at the start. Noah had 9 stickers.9
- Take away the ones that went. 8 went, so we take them away.9 - 8 = 1
- Write the answer. 1
Check. Add back: 1 + 8 = 9. ✓
Watch out. Less means take away. Check your answer makes sense.
Total 18 marks. Allow about 18 minutes.
Exercise 8X Practice test questions
Non-calculatorMethod. Take the part you know away from the whole.
- Read the bond. The whole is 6 and one part is 1.6 and 1
- Take the part away. What is left is the other part.6 - 1 = 5
- Write the answer. 5
Check. Add back: 5 + 1 = 6. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.8
- Count on 1 more. We add 1 to 8.8 + 1
- Write the answer. 9
Check. Count on from the other number too. You get 9 both ways.
Watch out. Count on, do not start again from one.
Method. Take the part you know away from the whole.
- Read the bond. The whole is 9 and one part is 8.9 and 8
- Take the part away. What is left is the other part.9 - 8 = 1
- Write the answer. 1
Check. Add back: 1 + 8 = 9. ✓
Watch out. The bond gives you the subtraction fact too.
Method. Put the two groups together. Start at the bigger number and count on.
- Start at the bigger number. It is quicker to count on from the bigger one.7
- Count on 1 more. We add 1 to 7.7 + 1
- Write the answer. 8
Check. Count on from the other number too. You get 8 both ways.
Watch out. Count on, do not start again from one.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.5
- Take away 3. Cross out or count back this many.5 - 3
- Write the answer. This is how many are left.2
Check. Add back: 2 + 3 = 5. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Take away the second number from the first. Count back to check.
- Start with the first number. It is the number of things we begin with.10
- Take away 8. Cross out or count back this many.10 - 8
- Write the answer. This is how many are left.2
Check. Add back: 2 + 8 = 10. The answer is right.
Watch out. Count back from the first number, not up from the second.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 7 and the known part is 4.7 and 4
- Count on from the known part to the whole. Or take the known part away from the whole.7 - 4 = 3
- Write the missing part. 3
Check. Put the two parts back together: 4 and 3 make 7.
Watch out. The two parts always add up to the whole.
Method. Find the missing part. Ask what goes with the known part to make the whole.
- Look at the whole and the part you know. The whole is 5 and the known part is 3.5 and 3
- Count on from the known part to the whole. Or take the known part away from the whole.5 - 3 = 2
- Write the missing part. 2
Check. Put the two parts back together: 3 and 2 make 5.
Watch out. The two parts always add up to the whole.
Method. Adding means we get more. Start with what there was and add the new ones.
- Start with the number at the start. Amira had 2 pencils.2
- Add the new ones. 6 more came, so we add them.2 + 6 = 8
- Write the answer. 8
Check. Count on 6 from 2: you reach 8. ✓
Watch out. More means add. Less means take away.
Method. Taking away means we get fewer. Start with the number at the start, then take away.
- Start with the number at the start. Noah had 3 stickers.3
- Take away the ones that went. 2 went, so we take them away.3 - 2 = 1
- Write the answer. 1
Check. Add back: 1 + 2 = 3. ✓
Watch out. Less means take away. Check your answer makes sense.