Year 1 Numbers to 100: worked examples and questions with answers
By the end of this chapter you will be able to
- Count forwards and backwards to 100, starting from any number
- Use the 100 square to count on and back
- Count in tens, and say 10 more and 10 less
- Say how many tens and ones a number has, and write it in numerals
- Say one more and one less, even when the number crosses a ten
- Say which of two numbers to 100 is bigger, and put numbers in order
You should already know
- Numbers to 10 (Chapter 1)
- Numbers to 20 (Chapter 4)
- Comparing groups and numbers (Chapter 1)
Where this leads
- Counting in twos, fives and tens to make equal groups (Chapter 9)
- Money in 10p coins (Chapter 12)
- Numbers to 100 in Year 2
National Curriculum for England, Key Stage 1 mathematics, Year 1. Content: Count to and across 100, forwards and backwards, from any number, Count, read and write numbers to 100 in numerals, Count in tens, Tens and ones to 100, One more and one less, Compare numbers to 100, The 100 square.
- 6.1 Counting to 100 on the 100 square: Worksheet (PDF) · Answers (PDF) · lesson page
- 6.2 Counting in tens: Worksheet (PDF) · Answers (PDF) · lesson page
- 6.3 Tens and ones: Worksheet (PDF) · Answers (PDF) · lesson page
- 6.4 One more and one less: Worksheet (PDF) · Answers (PDF) · lesson page
- 6.5 Comparing and ordering numbers to 100: Worksheet (PDF) · Answers (PDF) · lesson page
- Check-up and end-of-chapter quiz: Worksheet (PDF) · Answers (PDF) · lesson page
Exercise P Do you remember?
Non-calculatorKey words. To count is to say one number for each thing, in order.
Method. Say one number for each one, and touch each one only once. The last number you say is how many there are.
- Count each one and say its number. Each one gets one number. Do not miss one and do not count one twice.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12
- Look at the last number you said. The last number tells us how many there are altogether.The last number is 12.
- Write the answer. There are 12 stars.
Check. Count again from the other side. You get 12 again. ✓
Watch out. Move each one to one side as you count it, so you do not lose your place.
Key words. After means one more. Before means one less.
Method. After means one more. Find 14 on the 100 square first.
- Find 14 on the 100 square. 14 is 1 ten and 4 ones.14 = 1 ten and 4 ones
- Move one step on. After means one more. Move one step on.14 + 1 = 15
- Write the answer. 15
Check. Count on one from 14 and you say 15. ✓
Watch out. Do not write 14 again. The answer is the next number.
Key words. To count on is to say the next numbers in order, one more each time.
Method. Start at 15. Say the next number each time, one at a time.
- Start at 15. Put your finger on the number you start from.Start: 15
- Say 4 numbers, one at a time. Each new number is one more than the one before.16, 17, 18, 19
- Write the numbers in order. Write each number you said.16, 17, 18, 19
Check. Count back from 19 to 15 with your finger. The same numbers come again. ✓
Watch out. Do not say 15 again. Start with the number after it.
Method. Look at the tens first. The biggest number has the most tens.
- Look at the tens of each number. Compare the tens first.12: 1 tens 9: 0 tens
- Find the biggest number. Look for the most tens, then the ones.12 is the biggest number
- Write the answer. 12
Check. Put the numbers in order to check. ✓
Watch out. Do not pick the number with the biggest ones digit. Look at the tens first.
Method. Each number is 1 less than the one before it.
- Look at the numbers around each gap. The numbers go up or down by the same amount each time.20, 19, ?, 17
- Work out each missing number. Use the number before the gap, and take away 1.Gap 3: 19 − 1 = 18
- Write the missing numbers. 18
Check. Read the whole line again. Every number is 1 less than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go on by the same amount.
Counting to 100 on the 100 square
Printable: Worksheet (PDF) · Answers (PDF) · Open this lesson on its own page
We can count all the way to 100. The 100 square helps us see the numbers in order. It has ten rows, and each row has ten numbers. Read each row from left to right. When a row ends, the next number starts the next row.
You can start counting from any number. Count on to go up. Count back to go down. The purple box is 47. Put your finger on it and count on.
Key ideas
- The 100 square shows the numbers 1 to 100.
- Each row has ten numbers.
- Count on to go forwards. Count back to go backwards.
- When a row ends, the next number starts the next row.
Key words. To count on is to say the next numbers in order, one more each time.
Method. Start at 47. Say the next number each time, one at a time.
- Start at 47. Put your finger on the number you start from.Start: 47
- Say 4 numbers, one at a time. Each new number is one more than the one before.48, 49, 50, 51
- Write the numbers in order. Write each number you said.48, 49, 50, 51
Check. Count back from 51 to 47 with your finger. The same numbers come again. ✓
Watch out. Do not say 47 again. Start with the number after it.
Key words. To count back is to say the numbers before, one less each time.
Method. Start at 30. Say the number before it, then the one before that.
- Start at 30. Put your finger on the number you start from.Start: 30
- Say 4 numbers, going back. Each number is one less than the one before.29, 28, 27, 26
- Write the numbers in order. Write each number you said.29, 28, 27, 26
Check. Count on from 26 to 30 to check. The same numbers come again. ✓
Watch out. Do not say 30 again. Start with the number just before it.
Key words. After means one more. Before means one less.
Method. After means one more. Find 69 on the 100 square first.
- Find 69 on the 100 square. 69 is 6 tens and 9 ones.69 = 6 tens and 9 ones
- Move one step on. This number is at the end of a row. The next number starts the next row.69 + 1 = 70
- Write the answer. 70
Check. Count on one from 69 and you say 70. ✓
Watch out. Do not write 69 again. The answer is the next number.
Watch out
Watch out: after 69 comes 70. Do not write 610. The row ends at 69, so 70 starts the next row.
Exam tip
Grown-up tip. Print a 100 square, or draw one on paper. Ask your child to point with a finger as they count. Start at different numbers, such as 34 or 58, and count on and back.
Exercise 6A Counting to 100
Non-calculatorKey words. To count on is to say the next numbers in order, one more each time.
Method. Start at 14. Say the next number each time, one at a time.
- Start at 14. Put your finger on the number you start from.Start: 14
- Say 3 numbers, one at a time. Each new number is one more than the one before.15, 16, 17
- Write the numbers in order. Write each number you said.15, 16, 17
Check. Count back from 17 to 14 with your finger. The same numbers come again. ✓
Watch out. Do not say 14 again. Start with the number after it.
Key words. To count back is to say the numbers before, one less each time.
Method. Start at 30. Say the number before it, then the one before that.
- Start at 30. Put your finger on the number you start from.Start: 30
- Say 3 numbers, going back. Each number is one less than the one before.29, 28, 27
- Write the numbers in order. Write each number you said.29, 28, 27
Check. Count on from 27 to 30 to check. The same numbers come again. ✓
Watch out. Do not say 30 again. Start with the number just before it.
Key words. After means one more. Before means one less.
Method. After means one more. Find 49 on the 100 square first.
- Find 49 on the 100 square. 49 is 4 tens and 9 ones.49 = 4 tens and 9 ones
- Move one step on. This number is at the end of a row. The next number starts the next row.49 + 1 = 50
- Write the answer. 50
Check. Count on one from 49 and you say 50. ✓
Watch out. Do not write 49 again. The answer is the next number.
Key words. After means one more. Before means one less.
Method. Before means one less. Find 81 on the 100 square first.
- Find 81 on the 100 square. 81 is 8 tens and 1 one.81 = 8 tens and 1 one
- Move one step back. Before means one less. Move one step back.81 − 1 = 80
- Write the answer. 80
Check. Count back one from 81 and you say 80. ✓
Watch out. Do not write 81 again. The answer is the number just before.
Key words. To count on is to say the next numbers in order, one more each time.
Method. Start at 60. Say the next number each time, one at a time.
- Start at 60. Put your finger on the number you start from.Start: 60
- Say 5 numbers, one at a time. Each new number is one more than the one before.61, 62, 63, 64, 65
- Write the numbers in order. Write each number you said.61, 62, 63, 64, 65
Check. Count back from 65 to 60 with your finger. The same numbers come again. ✓
Watch out. Do not say 60 again. Start with the number after it.
Method. Each number is 1 more than the one before it.
- Look at the numbers around each gap. The numbers go up or down by the same amount each time.71, 72, ?, 74, ?, 76
- Work out each missing number. Use the number before the gap, and add 1.Gap 3: 72 + 1 = 73
Gap 5: 74 + 1 = 75 - Write the missing numbers. 73, 75
Check. Read the whole line again. Every number is 1 more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go on by the same amount.
Method. Use the numbers above and below each empty box. Going down one row adds 10.
- Look above and below each empty box. The number above is 10 less. The number below is 10 more.33: 23 above, 43 below
- Work out each missing number. The empty box is 10 more than the number above it.23 + 10 = 33
- Write the missing numbers. 33
Check. Check it: the number below each box is 10 more than the box. ✓
Watch out. Look up or down the column. Do not guess from the numbers next to the box.
Key words. To count back is to say the numbers before, one less each time.
Method. Start at 100. Say the number before it, then the one before that.
- Start at 100. Put your finger on the number you start from.Start: 100
- Say 5 numbers, going back. Each number is one less than the one before.99, 98, 97, 96, 95
- Write the numbers in order. Write each number you said.99, 98, 97, 96, 95
Check. Count on from 95 to 100 to check. The same numbers come again. ✓
Watch out. Do not say 100 again. Start with the number just before it.
Key words. After means one more. Before means one less.
Method. After means one more. Find 39 on the 100 square first.
- Find 39 on the 100 square. 39 is 3 tens and 9 ones.39 = 3 tens and 9 ones
- Move one step on. This number is at the end of a row. The next number starts the next row.39 + 1 = 40
- Write the answer. 40
Check. Count on one from 39 and you say 40. ✓
Watch out. Do not write 39 again. The answer is the next number.
Method. Count from 90 to 100, and count how many numbers you said.
- Count from 90 to 100. Say every number, including the first and the last.90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100
- Count how many numbers you said. Count each number in your list once.11 numbers
- Write the answer. 11
Check. Count on from 90 for 10 more numbers. You land on 100. ✓
Watch out. Remember to count 90 and 100 as well. They are both in the list.
Key words. To count on is to say the next numbers in order, one more each time.
Method. Start at 27. Say the next number each time, one at a time.
- Start at 27. Put your finger on the number you start from.Start: 27
- Say 6 numbers, one at a time. Each new number is one more than the one before.28, 29, 30, 31, 32, 33
- Write the numbers in order. Write each number you said.28, 29, 30, 31, 32, 33
Check. Count back from 33 to 27 with your finger. The same numbers come again. ✓
Watch out. Do not say 27 again. Start with the number after it.
Key words. To count on is to say the next numbers in order, one more each time.
Method. Start at 58. Say the next number each time, one at a time.
- Start at 58. Put your finger on the number you start from.Start: 58
- Say 3 numbers, one at a time. Each new number is one more than the one before.59, 60, 61
- Write the numbers in order. Write each number you said.59, 60, 61
Check. Count back from 61 to 58 with your finger. The same numbers come again. ✓
Watch out. Do not say 58 again. Start with the number after it.
Counting in tens
Printable: Worksheet (PDF) · Answers (PDF) · Open this lesson on its own page
Some numbers are tens. The tens are 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100. Each one is ten more than the number before it. So when we count in tens, we jump one ten each time.
The shaded numbers on this square are the tens. They are all in the right-hand column, because each one is the last number in its row.
Key ideas
- The tens are 10, 20, 30 and so on, up to 100.
- Counting in tens: each number is 10 more than the one before.
- 10 more: move down one row on the 100 square.
- 10 less: move up one row on the 100 square.
Method. Count in tens. Each number is 10 more than the one before.
- Start at 30. Put your finger on the first ten.Start: 30
- Jump on one ten each time. Change only the tens. The ones stay at 0.30, 40, 50, 60
- Write the numbers. 30, 40, 50, 60
Check. Count back in tens from 60 to 30 to check. ✓
Watch out. Change the tens, not the ones. When you count in tens, the ones digit is always 0.
Method. 10 more means one row down on the 100 square. Only the tens change.
- Find 47. 47 is 4 tens and 7 ones.47 = 4 tens and 7 ones
- Change the tens. Add one ten. The ones stay the same.5 tens and 7 ones
- Write the answer. 57
Check. 47 + 10 = 57. ✓
Watch out. Only the tens change. 47 becomes 57, not 48.
Method. 10 less means one row up on the 100 square. Only the tens change.
- Find 83. 83 is 8 tens and 3 ones.83 = 8 tens and 3 ones
- Change the tens. Take away one ten. The ones stay the same.7 tens and 3 ones
- Write the answer. 73
Check. 83 − 10 = 73. ✓
Watch out. Only the tens change. 83 becomes 73, not 82.
Watch out
Watch out: only the tens digit changes. 47 + 10 is 57, not 48. The ones stay the same.
Exam tip
Grown-up tip. Count in tens aloud while your child taps down a column of a 100 square. Ask: “What is 10 more than 25?” Then check on the square together.
Exercise 6B Counting in tens
Non-calculatorMethod. Count on in tens from 10.
- Start at 10. Put your finger on the starting number.Start: 10
- Add 10 each time. Change the tens. The ones stay at 0.20, 30, 40
- Write the next 3 numbers. 20, 30, 40
Check. 10 + 10 = 20. ✓
Watch out. Do not write the starting number again. Start with the next one.
Method. Count back in tens from 90.
- Start at 90. Put your finger on the starting number.Start: 90
- Take away 10 each time. Change the tens. The ones stay at 0.80, 70, 60
- Write the next 3 numbers. 80, 70, 60
Check. 90 − 10 = 80. ✓
Watch out. Do not write the starting number again. Start with the next one.
Method. 10 more means one row down on the 100 square. Only the tens change.
- Find 20. 20 is 2 tens and 0 ones.20 = 2 tens and 0 ones
- Change the tens. Add one ten. The ones stay the same.3 tens and 0 ones
- Write the answer. 30
Check. 20 + 10 = 30. ✓
Watch out. Only the tens change. 20 becomes 30, not 21.
Method. 10 less means one row up on the 100 square. Only the tens change.
- Find 70. 70 is 7 tens and 0 ones.70 = 7 tens and 0 ones
- Change the tens. Take away one ten. The ones stay the same.6 tens and 0 ones
- Write the answer. 60
Check. 70 − 10 = 60. ✓
Watch out. Only the tens change. 70 becomes 60, not 69.
Method. 10 more means one row down on the 100 square. Only the tens change.
- Find 35. 35 is 3 tens and 5 ones.35 = 3 tens and 5 ones
- Change the tens. Add one ten. The ones stay the same.4 tens and 5 ones
- Write the answer. 45
Check. 35 + 10 = 45. ✓
Watch out. Only the tens change. 35 becomes 45, not 36.
Method. 10 less means one row up on the 100 square. Only the tens change.
- Find 58. 58 is 5 tens and 8 ones.58 = 5 tens and 8 ones
- Change the tens. Take away one ten. The ones stay the same.4 tens and 8 ones
- Write the answer. 48
Check. 58 − 10 = 48. ✓
Watch out. Only the tens change. 58 becomes 48, not 57.
Method. Each number is 10 more than the one before it.
- Look at the numbers around each gap. The numbers go up or down by the same amount each time.40, 50, ?, 70, ?, 90
- Work out each missing number. Use the number before the gap, and add 10.Gap 3: 50 + 10 = 60
Gap 5: 70 + 10 = 80 - Write the missing numbers. 60, 80
Check. Read the whole line again. Every number is 10 more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go on by the same amount.
Method. Use the numbers above and below each empty box. Going down one row adds 10.
- Look above and below each empty box. The number above is 10 less. The number below is 10 more.30: 20 above, 40 below; 70: 60 above, 80 below
- Work out each missing number. The empty box is 10 more than the number above it.20 + 10 = 30
60 + 10 = 70 - Write the missing numbers. 30, 70
Check. Check it: the number below each box is 10 more than the box. ✓
Watch out. Look up or down the column. Do not guess from the numbers next to the box.
Method. 10 more means one row down on the 100 square. Only the tens change.
- Find 45. 45 is 4 tens and 5 ones.45 = 4 tens and 5 ones
- Change the tens. Add one ten. The ones stay the same.5 tens and 5 ones
- Write the answer. 55
Check. 45 + 10 = 55. ✓
Watch out. Only the tens change. 45 becomes 55, not 46.
Method. Each pack has 10 things. Count the tens to find the total.
- Count the packs: 3. Each pack has 10 in it.3 packs of 10
- Count in tens, one ten for each pack. Add 10 for every pack you count.10, 20, 30
- Write the total. 30
Check. Count in tens to check: the last number you say is 30. ✓
Watch out. Count in tens, not in ones. Each pack is one ten.
Method. Count in tens. Each number is 10 more than the one before.
- Start at 30. Put your finger on the first ten.Start: 30
- Jump on one ten each time. Change only the tens. The ones stay at 0.30, 40, 50
- Write the numbers. 30, 40, 50
Check. Count back in tens from 50 to 30 to check. ✓
Watch out. Change the tens, not the ones. When you count in tens, the ones digit is always 0.
Method. Look at the numbers in the right-hand column of the 100 square.
- Look at the numbers in the column. These are the numbers that end a row.10, 20, 30, 40, 50 and so on
- Look at the ones digit. Every one of them has 0 ones.Ones digit: 0 for every number
- Write the answer. They all end in 0.
Check. 10, 20 and 30 all have 0 ones, so the ones digit is 0. ✓
Watch out. A number that ends in 0 is a ten. The 0 is the ones digit.
Tens and ones
Printable: Worksheet (PDF) · Answers (PDF) · Open this lesson on its own page
Every number to 100 is made of tens and ones. A ten is a long bar with ten squares on it. A one is a single small square. Ten ones make one ten.
The number 47 has 4 tens and 7 ones. The tens go on the left. The ones go on the right.
| Tens | Ones |
|---|---|
| 4 | 7 |
Key ideas
- A ten is a bundle of ten ones.
- The tens digit goes on the left.
- The ones digit goes on the right.
- 100 is ten tens and no ones.
Key words. A ten is a bundle of ten ones. A one is a single thing.
Method. Count the groups of ten first. Then count the ones left over.
- Count the tens in 35. Each group of ten is one ten.30 is 3 tens
- Count the ones left over. The ones are what is left after the tens.35 − 30 = 5 ones
- Write the answer. 3 tens and 5 ones
Check. Put them back together: 30 + 5 = 35. ✓
Watch out. The tens come first when you say the number. 25 is 2 tens and 5 ones, not 5 tens and 2 ones.
Method. Start with the tens, then add the ones.
- Write 6 tens. The tens go on the left.6 tens = 60
- Add 2 ones. The ones go on the right, after the tens.60 + 2 = 62
- Write the number. 62
Check. Read it back: 62 has 6 tens and 2 ones. ✓
Watch out. The tens digit goes on the left. Write 6 tens and 2 ones as 62, not 26.
Method. Count how many groups of ten there are.
- Count the groups of ten in 100. Count in tens: 10, 20 and so on.10 tens = 100
- Check the ones left over. The ones are not tens, so they do not count here.0 ones left over
- Write the answer. The number of tens is the number on the left.10
Check. 10 tens and 0 ones make 100. ✓
Watch out. Count the tens, not the ones. For 90, there are 9 tens and 0 ones.
Watch out
Watch out: the tens digit goes on the left. 25 has 2 tens and 5 ones. It does not have 5 tens and 2 ones.
Exam tip
Grown-up tip. Put 10 pasta shapes or buttons in a cup. The cup is one ten. Keep the loose ones on the table. Ask: “How many cups? How many loose ones?”
Exercise 6C Tens and ones
Non-calculatorKey words. A ten is a bundle of ten ones. A one is a single thing.
Method. Count the groups of ten first. Then count the ones left over.
- Count the tens in 23. Each group of ten is one ten.20 is 2 tens
- Count the ones left over. The ones are what is left after the tens.23 − 20 = 3 ones
- Write the answer. 2 tens and 3 ones
Check. Put them back together: 20 + 3 = 23. ✓
Watch out. The tens come first when you say the number. 25 is 2 tens and 5 ones, not 5 tens and 2 ones.
Key words. A ten is a bundle of ten ones. A one is a single thing.
Method. Count the groups of ten first. Then count the ones left over.
- Count the tens in 58. Each group of ten is one ten.50 is 5 tens
- Count the ones left over. The ones are what is left after the tens.58 − 50 = 8 ones
- Write the answer. 5 tens and 8 ones
Check. Put them back together: 50 + 8 = 58. ✓
Watch out. The tens come first when you say the number. 25 is 2 tens and 5 ones, not 5 tens and 2 ones.
Method. The ones are the number left over after the tens.
- Take away the groups of ten from 69. Take away all the tens.69 − 60 = 9
- Count what is left. These are the ones.9 ones
- Write the answer. 9
Check. 60 + 9 = 69. ✓
Watch out. The ones digit is the last digit of the number.
Method. Count how many groups of ten there are.
- Count the groups of ten in 90. Count in tens: 10, 20 and so on.9 tens = 90
- Check the ones left over. The ones are not tens, so they do not count here.0 ones left over
- Write the answer. The number of tens is the number on the left.9
Check. 9 tens and 0 ones make 90. ✓
Watch out. Count the tens, not the ones. For 90, there are 9 tens and 0 ones.
Method. Start with the tens, then add the ones.
- Write 5 tens. The tens go on the left.5 tens = 50
- Add 4 ones. The ones go on the right, after the tens.50 + 4 = 54
- Write the number. 54
Check. Read it back: 54 has 5 tens and 4 ones. ✓
Watch out. The tens digit goes on the left. Write 5 tens and 4 ones as 54, not 45.
Method. Start with the tens, then add the ones.
- Write 8 tens. The tens go on the left.8 tens = 80
- Add 0 ones. The ones go on the right, after the tens.80 + 0 = 80
- Write the number. 80
Check. Read it back: 80 has 8 tens and 0 ones. ✓
Watch out. The tens digit goes on the left. Write 8 tens and 0 ones as 80, not 08.
Method. Start with the tens, then add the ones.
- Write 1 ten. The tens go on the left.1 tens = 10
- Add 9 ones. The ones go on the right, after the tens.10 + 9 = 19
- Write the number. 19
Check. Read it back: 19 has 1 tens and 9 ones. ✓
Watch out. The tens digit goes on the left. Write 1 tens and 9 ones as 19, not 91.
Method. Start with the tens, then add the ones.
- Write 6 tens. The tens go on the left.6 tens = 60
- Add 2 ones. The ones go on the right, after the tens.60 + 2 = 62
- Write the number. 62
Check. Read it back: 62 has 6 tens and 2 ones. ✓
Watch out. The tens digit goes on the left. Write 6 tens and 2 ones as 62, not 26.
Key words. A ten is a bundle of ten ones. A one is a single thing.
Method. Count the groups of ten first. Then count the ones left over.
- Count the tens in 36. Each group of ten is one ten.30 is 3 tens
- Count the ones left over. The ones are what is left after the tens.36 − 30 = 6 ones
- Write the answer. 3 tens and 6 ones
Check. Put them back together: 30 + 6 = 36. ✓
Watch out. The tens come first when you say the number. 25 is 2 tens and 5 ones, not 5 tens and 2 ones.
Key words. A ten is a bundle of ten ones. A one is a single thing.
Method. Count the groups of ten first. Then count the ones left over.
- Count the tens in 50. Each group of ten is one ten.50 is 5 tens
- Count the ones left over. The ones are what is left after the tens.50 − 50 = 0 ones
- Write the answer. 5 tens and 0 ones
Check. Put them back together: 50 + 0 = 50. ✓
Watch out. The tens come first when you say the number. 25 is 2 tens and 5 ones, not 5 tens and 2 ones.
Key words. A ten is a bundle of ten ones. A one is a single thing.
Method. Count the groups of ten first. Then count the ones left over.
- Count the tens in 81. Each group of ten is one ten.80 is 8 tens
- Count the ones left over. The ones are what is left after the tens.81 − 80 = 1 one
- Write the answer. 8 tens and 1 one
Check. Put them back together: 80 + 1 = 81. ✓
Watch out. The tens come first when you say the number. 25 is 2 tens and 5 ones, not 5 tens and 2 ones.
Method. Start with the tens, then add the ones.
- Write 3 tens. The tens go on the left.3 tens = 30
- Add 4 ones. The ones go on the right, after the tens.30 + 4 = 34
- Write the number. 34
Check. Read it back: 34 has 3 tens and 4 ones. ✓
Watch out. The tens digit goes on the left. Write 3 tens and 4 ones as 34, not 43.
Key words. A ten is a bundle of ten ones. A one is a single thing.
Method. Count the groups of ten first. Then count the ones left over.
- Count the tens in 62. Each group of ten is one ten.60 is 6 tens
- Count the ones left over. The ones are what is left after the tens.62 − 60 = 2 ones
- Write the answer. 6 tens and 2 ones
Check. Put them back together: 60 + 2 = 62. ✓
Watch out. The tens come first when you say the number. 25 is 2 tens and 5 ones, not 5 tens and 2 ones.
Method. Most of the numbers have 7 tens. Find the one that does not.
- Look at the tens of each number. Count the tens in each number.72: 7 tens 17: 1 tens 74: 7 tens 79: 7 tens
- Find the one that is different. 17 has 1 tens. The others have 7 tens.17 is different
- Write the answer. 17
Check. Check each of the others: they all have 7 tens. ✓
Watch out. Look at the tens, not at the ones.
One more and one less
Printable: Worksheet (PDF) · Answers (PDF) · Open this lesson on its own page
One more is the number that comes next. One less is the number that comes just before. On the 100 square, one more is one step to the right. One less is one step to the left.
Be careful at the end of a row. One more than 39 is 40, because 40 starts the next row.
Key ideas
- One more is the next number. Count on one.
- One less is the number before. Count back one.
- Across a ten: 39 + 1 is 40, and 40 − 1 is 39.
- Check your answer by counting on or back from the number.
Key words. After means one more. Before means one less.
Method. After means one more. Find 39 on the 100 square first.
- Find 39 on the 100 square. 39 is 3 tens and 9 ones.39 = 3 tens and 9 ones
- Move one step on. This number is at the end of a row. The next number starts the next row.39 + 1 = 40
- Write the answer. 40
Check. Count on one from 39 and you say 40. ✓
Watch out. Do not write 39 again. The answer is the next number.
Key words. After means one more. Before means one less.
Method. Before means one less. Find 60 on the 100 square first.
- Find 60 on the 100 square. 60 is 6 tens and 0 ones.60 = 6 tens and 0 ones
- Move one step back. Before means one less. Move one step back.60 − 1 = 59
- Write the answer. 59
Check. Count back one from 60 and you say 59. ✓
Watch out. Do not write 60 again. The answer is the number just before.
Method. One less is the number before. One more is the number after.
- Find one less than 50. Count back one from the number.50 − 1 = 49
- Find one more than 50. Count on one from the number.50 + 1 = 51
- Write the answer. 49 and 51
Check. Count in order: 49, 50, 51. ✓
Watch out. Check the number in the middle is the number you started with.
Watch out
Watch out: when a number ends in 9, one more changes the tens. 39 + 1 is 40, not 30.
Exam tip
Grown-up tip. Point to a number on a 100 square. Move one square right for one more, and one square left for one less. Ask: “What is one more than 49?” and see if your child moves into the next row.
Exercise 6D One more and one less
Non-calculatorKey words. After means one more. Before means one less.
Method. After means one more. Find 14 on the 100 square first.
- Find 14 on the 100 square. 14 is 1 ten and 4 ones.14 = 1 ten and 4 ones
- Move one step on. After means one more. Move one step on.14 + 1 = 15
- Write the answer. 15
Check. Count on one from 14 and you say 15. ✓
Watch out. Do not write 14 again. The answer is the next number.
Key words. After means one more. Before means one less.
Method. Before means one less. Find 27 on the 100 square first.
- Find 27 on the 100 square. 27 is 2 tens and 7 ones.27 = 2 tens and 7 ones
- Move one step back. Before means one less. Move one step back.27 − 1 = 26
- Write the answer. 26
Check. Count back one from 27 and you say 26. ✓
Watch out. Do not write 27 again. The answer is the number just before.
Key words. After means one more. Before means one less.
Method. After means one more. Find 59 on the 100 square first.
- Find 59 on the 100 square. 59 is 5 tens and 9 ones.59 = 5 tens and 9 ones
- Move one step on. This number is at the end of a row. The next number starts the next row.59 + 1 = 60
- Write the answer. 60
Check. Count on one from 59 and you say 60. ✓
Watch out. Do not write 59 again. The answer is the next number.
Key words. After means one more. Before means one less.
Method. Before means one less. Find 70 on the 100 square first.
- Find 70 on the 100 square. 70 is 7 tens and 0 ones.70 = 7 tens and 0 ones
- Move one step back. Before means one less. Move one step back.70 − 1 = 69
- Write the answer. 69
Check. Count back one from 70 and you say 69. ✓
Watch out. Do not write 70 again. The answer is the number just before.
Key words. After means one more. Before means one less.
Method. After means one more. Find 99 on the 100 square first.
- Find 99 on the 100 square. 99 is 9 tens and 9 ones.99 = 9 tens and 9 ones
- Move one step on. This number is at the end of a row. The next number starts the next row.99 + 1 = 100
- Write the answer. 100
Check. Count on one from 99 and you say 100. ✓
Watch out. Do not write 99 again. The answer is the next number.
Key words. After means one more. Before means one less.
Method. After means one more. Find 36 on the 100 square first.
- Find 36 on the 100 square. 36 is 3 tens and 6 ones.36 = 3 tens and 6 ones
- Move one step on. After means one more. Move one step on.36 + 1 = 37
- Write the answer. 37
Check. Count on one from 36 and you say 37. ✓
Watch out. Do not write 36 again. The answer is the next number.
Key words. After means one more. Before means one less.
Method. After means one more. Find 48 on the 100 square first.
- Find 48 on the 100 square. 48 is 4 tens and 8 ones.48 = 4 tens and 8 ones
- Move one step on. After means one more. Move one step on.48 + 1 = 49
- Write the answer. 49
Check. Count on one from 48 and you say 49. ✓
Watch out. Do not write 48 again. The answer is the next number.
Key words. After means one more. Before means one less.
Method. After means one more. Find 90 on the 100 square first.
- Find 90 on the 100 square. 90 is 9 tens and 0 ones.90 = 9 tens and 0 ones
- Move one step on. After means one more. Move one step on.90 + 1 = 91
- Write the answer. 91
Check. Count on one from 90 and you say 91. ✓
Watch out. Do not write 90 again. The answer is the next number.
Key words. After means one more. Before means one less.
Method. Before means one less. Find 41 on the 100 square first.
- Find 41 on the 100 square. 41 is 4 tens and 1 one.41 = 4 tens and 1 one
- Move one step back. Before means one less. Move one step back.41 − 1 = 40
- Write the answer. 40
Check. Count back one from 41 and you say 40. ✓
Watch out. Do not write 41 again. The answer is the number just before.
Key words. After means one more. Before means one less.
Method. Before means one less. Find 50 on the 100 square first.
- Find 50 on the 100 square. 50 is 5 tens and 0 ones.50 = 5 tens and 0 ones
- Move one step back. Before means one less. Move one step back.50 − 1 = 49
- Write the answer. 49
Check. Count back one from 50 and you say 49. ✓
Watch out. Do not write 50 again. The answer is the number just before.
Key words. After means one more. Before means one less.
Method. Before means one less. Find 100 on the 100 square first.
- Find 100 on the 100 square. 100 is 10 tens and 0 ones.100 = 10 tens and 0 ones
- Move one step back. Before means one less. Move one step back.100 − 1 = 99
- Write the answer. 99
Check. Count back one from 100 and you say 99. ✓
Watch out. Do not write 100 again. The answer is the number just before.
Key words. After means one more. Before means one less.
Method. After means one more. Find 64 on the 100 square first.
- Find 64 on the 100 square. 64 is 6 tens and 4 ones.64 = 6 tens and 4 ones
- Move one step on. After means one more. Move one step on.64 + 1 = 65
- Write the answer. 65
Check. Count on one from 64 and you say 65. ✓
Watch out. Do not write 64 again. The answer is the next number.
Key words. After means one more. Before means one less.
Method. Before means one less. Find 40 on the 100 square first.
- Find 40 on the 100 square. 40 is 4 tens and 0 ones.40 = 4 tens and 0 ones
- Move one step back. Before means one less. Move one step back.40 − 1 = 39
- Write the answer. 39
Check. Count back one from 40 and you say 39. ✓
Watch out. Do not write 40 again. The answer is the number just before.
Key words. After means one more. Before means one less.
Method. After means one more. Find 49 on the 100 square first.
- Find 49 on the 100 square. 49 is 4 tens and 9 ones.49 = 4 tens and 9 ones
- Move one step on. This number is at the end of a row. The next number starts the next row.49 + 1 = 50
- Write the answer. 50
Check. Count on one from 49 and you say 50. ✓
Watch out. Do not write 49 again. The answer is the next number.
Key words. After means one more. Before means one less.
Method. Before means one less. Find 37 on the 100 square first.
- Find 37 on the 100 square. 37 is 3 tens and 7 ones.37 = 3 tens and 7 ones
- Move one step back. Before means one less. Move one step back.37 − 1 = 36
- Write the answer. 36
Check. Count back one from 37 and you say 36. ✓
Watch out. Do not write 37 again. The answer is the number just before.
Key words. To count on is to say the next numbers in order, one more each time.
Method. Start at 45. Say the next number each time, one at a time.
- Start at 45. Put your finger on the number you start from.Start: 45
- Say 10 numbers, one at a time. Each new number is one more than the one before.46, 47, 48, 49, 50, 51, 52, 53, 54, 55
- Write the numbers in order. Write each number you said.46, 47, 48, 49, 50, 51, 52, 53, 54, 55
Check. Count back from 55 to 45 with your finger. The same numbers come again. ✓
Watch out. Do not say 45 again. Start with the number after it.
Comparing and ordering numbers to 100
Printable: Worksheet (PDF) · Answers (PDF) · Open this lesson on its own page
To compare two numbers, look at the tens first. The number with more tens is the bigger number. If both numbers have the same tens, look at the ones.
Each long bar is a ten. Each small square is a one. Which pile has more?
On a number line, bigger numbers are further to the right.
Key ideas
- Look at the tens first.
- More tens means a bigger number.
- If the tens are the same, compare the ones.
- Put numbers in order by their tens, then their ones.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.47: 4 tens 52: 5 tens
- Compare the tens. The number with more tens is the bigger number.5 tens is more than 4 tens
- Write the answer. Bigger means more.52
Check. On the 100 square, 52 is further along than 47. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.38: 3 tens 35: 3 tens
- The tens are the same, so look at the ones. When the tens match, the ones decide.38: 8 ones 35: 5 ones
- Compare the ones. The number with more ones is the bigger one.8 is more than 5
- Write the answer. Bigger means more.38
Check. On the 100 square, 38 is further along than 35. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Smallest is the least. Biggest is the most.
Method. Compare the tens first, then the ones, and put the numbers in order.
- Look at the tens of each number. A number with fewer tens is smaller.63: 6 tens 36: 3 tens 90: 9 tens 58: 5 tens
- Put them in order, smallest first. Start with the smallest number, then the next one.36, 58, 63, 90
- Write the answer. 36, 58, 63, 90
Check. There are 4 numbers in the question and 4 in the answer. ✓
Watch out. Check you have not left a number out, and that each number is used once.
Watch out
Watch out: do not compare only the ones. 9 ones is more than 1 one, but 39 is smaller than 51. That is because 39 has 3 tens and 51 has 5 tens.
Exam tip
Grown-up tip. Write two or three numbers on cards and mix them up. Ask your child to put them in order, smallest first. Let them look at the tens before the ones.
Exercise 6E Comparing and ordering
Non-calculatorKey words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.26: 2 tens 62: 6 tens
- Compare the tens. The number with more tens is the bigger number.6 tens is more than 2 tens
- Write the answer. Bigger means more.62
Check. On the 100 square, 62 is further along than 26. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.45: 4 tens 49: 4 tens
- The tens are the same, so look at the ones. When the tens match, the ones decide.45: 5 ones 49: 9 ones
- Compare the ones. The number with more ones is the bigger one.9 is more than 5
- Write the answer. Smaller means less.45
Check. On the 100 square, 49 is further along than 45. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.70: 7 tens 67: 6 tens
- Compare the tens. The number with more tens is the bigger number.7 tens is more than 6 tens
- Write the answer. Bigger means more.70
Check. On the 100 square, 70 is further along than 67. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.Group A: 6 tens Group B: 5 tens
- Compare the tens. The number with more tens is the bigger number.6 tens is more than 5 tens
- Write the answer. Bigger means more.Group A
Check. On the 100 square, 63 is further along than 58. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Smallest is the least. Biggest is the most.
Method. Compare the tens first, then the ones, and put the numbers in order.
- Look at the tens of each number. A number with fewer tens is smaller.18: 1 tens 81: 8 tens 42: 4 tens
- Put them in order, smallest first. Start with the smallest number, then the next one.18, 42, 81
- Write the answer. 18, 42, 81
Check. There are 3 numbers in the question and 3 in the answer. ✓
Watch out. Check you have not left a number out, and that each number is used once.
Key words. Smallest is the least. Biggest is the most.
Method. Compare the tens first, then the ones, and put the numbers in order.
- Look at the tens of each number. A number with fewer tens is smaller.74: 7 tens 47: 4 tens 72: 7 tens 27: 2 tens
- Put them in order, biggest first. Start with the biggest number, then the next one.74, 72, 47, 27
- Write the answer. 74, 72, 47, 27
Check. There are 4 numbers in the question and 4 in the answer. ✓
Watch out. Check you have not left a number out, and that each number is used once.
Method. Look at the tens first. The biggest number has the most tens.
- Look at the tens of each number. Compare the tens first.58: 5 tens 85: 8 tens 52: 5 tens
- Find the biggest number. Look for the most tens, then the ones.85 is the biggest number
- Write the answer. 85
Check. Put the numbers in order to check. ✓
Watch out. Do not pick the number with the biggest ones digit. Look at the tens first.
Method. Look at the tens first. The smallest number has the fewest tens.
- Look at the tens of each number. Compare the tens first.31: 3 tens 29: 2 tens 60: 6 tens
- Find the smallest number. Look for the fewest tens, then the ones.29 is the smallest number
- Write the answer. 29
Check. Put the numbers in order to check. ✓
Watch out. Do not pick the number with the biggest ones digit. Look at the tens first.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.19: 1 tens 91: 9 tens
- Compare the tens. The number with more tens is the bigger number.9 tens is more than 1 tens
- Write the answer. Bigger means more.91
Check. On the 100 square, 91 is further along than 19. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.55: 5 tens 50: 5 tens
- The tens are the same, so look at the ones. When the tens match, the ones decide.55: 5 ones 50: 0 ones
- Compare the ones. The number with more ones is the bigger one.5 is more than 0
- Write the answer. Bigger means more.55
Check. On the 100 square, 55 is further along than 50. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.28: 2 tens 82: 8 tens
- Compare the tens. The number with more tens is the bigger number.8 tens is more than 2 tens
- Write the answer. Bigger means more.82
Check. On the 100 square, 82 is further along than 28. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.25: 2 tens 9: 0 tens
- Compare the tens. The number with more tens is the bigger number.2 tens is more than 0 tens
- Write the answer. Bigger means more.25
Check. On the 100 square, 25 is further along than 9. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.Mei: 5 tens Leo: 4 tens
- Compare the tens. The number with more tens is the bigger number.5 tens is more than 4 tens
- Write the answer. Bigger means more.Mei
Check. On the 100 square, 52 is further along than 47. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Smallest is the least. Biggest is the most.
Method. Compare the tens first, then the ones, and put the numbers in order.
- Look at the tens of each number. A number with fewer tens is smaller.34: 3 tens 43: 4 tens 39: 3 tens 30: 3 tens
- Put them in order, smallest first. Start with the smallest number, then the next one.30, 34, 39, 43
- Write the answer. 30, 34, 39, 43
Check. There are 4 numbers in the question and 4 in the answer. ✓
Watch out. Check you have not left a number out, and that each number is used once.
Chapter summary
| Skill | Method |
|---|---|
| Count to 100 | Count on to go forwards, count back to go backwards. The 100 square shows the order. |
| Count in tens | Each ten is 10 more than the one before. Change the tens, not the ones. |
| Tens and ones | The tens go on the left and the ones go on the right. 47 is 4 tens and 7 ones. |
| One more and one less | One more is the next number. One less is the number before. Watch the ends of rows. |
| Compare numbers | Look at the tens first. If the tens are the same, look at the ones. |
| Order numbers | Put numbers in order by their tens, then their ones. |
Can you…?
- I can count forwards and backwards to 100, from any number
- I can use the 100 square to count on and back
- I can count in tens, and say 10 more and 10 less
- I can say how many tens and ones a number has, and write it in numerals
- I can say one more and one less, even across a ten
- I can say which of two numbers to 100 is bigger, and put numbers in order
Key terms
- 100 square
- a grid with the numbers 1 to 100 in ten rows of ten
- ten
- a bundle of ten ones, or a number like 10, 20 or 30
- ones
- the single things, or the digit on the right of a number
- tens digit
- the digit on the left that tells us how many tens
- one more
- the next number
- one less
- the number just before
- compare
- to look at two numbers and say which is bigger or smaller
- in order
- going from smallest to biggest, or from biggest to smallest
Exercise 6Z Check-up
Non-calculatorKey words. To count on is to say the next numbers in order, one more each time.
Method. Start at 65. Say the next number each time, one at a time.
- Start at 65. Put your finger on the number you start from.Start: 65
- Say 3 numbers, one at a time. Each new number is one more than the one before.66, 67, 68
- Write the numbers in order. Write each number you said.66, 67, 68
Check. Count back from 68 to 65 with your finger. The same numbers come again. ✓
Watch out. Do not say 65 again. Start with the number after it.
Method. Count back in tens from 80.
- Start at 80. Put your finger on the starting number.Start: 80
- Take away 10 each time. Change the tens. The ones stay at 0.70, 60, 50
- Write the next 3 numbers. 70, 60, 50
Check. 80 − 10 = 70. ✓
Watch out. Do not write the starting number again. Start with the next one.
Key words. A ten is a bundle of ten ones. A one is a single thing.
Method. Count the groups of ten first. Then count the ones left over.
- Count the tens in 84. Each group of ten is one ten.80 is 8 tens
- Count the ones left over. The ones are what is left after the tens.84 − 80 = 4 ones
- Write the answer. 8 tens and 4 ones
Check. Put them back together: 80 + 4 = 84. ✓
Watch out. The tens come first when you say the number. 25 is 2 tens and 5 ones, not 5 tens and 2 ones.
Method. Start with the tens, then add the ones.
- Write 7 tens. The tens go on the left.7 tens = 70
- Add 3 ones. The ones go on the right, after the tens.70 + 3 = 73
- Write the number. 73
Check. Read it back: 73 has 7 tens and 3 ones. ✓
Watch out. The tens digit goes on the left. Write 7 tens and 3 ones as 73, not 37.
Key words. After means one more. Before means one less.
Method. After means one more. Find 48 on the 100 square first.
- Find 48 on the 100 square. 48 is 4 tens and 8 ones.48 = 4 tens and 8 ones
- Move one step on. After means one more. Move one step on.48 + 1 = 49
- Write the answer. 49
Check. Count on one from 48 and you say 49. ✓
Watch out. Do not write 48 again. The answer is the next number.
Key words. After means one more. Before means one less.
Method. Before means one less. Find 91 on the 100 square first.
- Find 91 on the 100 square. 91 is 9 tens and 1 one.91 = 9 tens and 1 one
- Move one step back. Before means one less. Move one step back.91 − 1 = 90
- Write the answer. 90
Check. Count back one from 91 and you say 90. ✓
Watch out. Do not write 91 again. The answer is the number just before.
Method. 10 more means one row down on the 100 square. Only the tens change.
- Find 52. 52 is 5 tens and 2 ones.52 = 5 tens and 2 ones
- Change the tens. Add one ten. The ones stay the same.6 tens and 2 ones
- Write the answer. 62
Check. 52 + 10 = 62. ✓
Watch out. Only the tens change. 52 becomes 62, not 53.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.74: 7 tens 47: 4 tens
- Compare the tens. The number with more tens is the bigger number.7 tens is more than 4 tens
- Write the answer. Bigger means more.74
Check. On the 100 square, 74 is further along than 47. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. Smallest is the least. Biggest is the most.
Method. Compare the tens first, then the ones, and put the numbers in order.
- Look at the tens of each number. A number with fewer tens is smaller.58: 5 tens 49: 4 tens 81: 8 tens 15: 1 tens
- Put them in order, smallest first. Start with the smallest number, then the next one.15, 49, 58, 81
- Write the answer. 15, 49, 58, 81
Check. There are 4 numbers in the question and 4 in the answer. ✓
Watch out. Check you have not left a number out, and that each number is used once.
Method. Use the numbers above and below each empty box. Going down one row adds 10.
- Look above and below each empty box. The number above is 10 less. The number below is 10 more.77: 67 above, 87 below
- Work out each missing number. The empty box is 10 more than the number above it.67 + 10 = 77
- Write the missing numbers. 77
Check. Check it: the number below each box is 10 more than the box. ✓
Watch out. Look up or down the column. Do not guess from the numbers next to the box.
Total 13 marks. Allow about 13 minutes.
Exercise 6X End-of-chapter quiz
Non-calculatorKey words. After means one more. Before means one less.
Method. After means one more. Find 79 on the 100 square first.
- Find 79 on the 100 square. 79 is 7 tens and 9 ones.79 = 7 tens and 9 ones
- Move one step on. This number is at the end of a row. The next number starts the next row.79 + 1 = 80
- Write the answer. 80
Check. Count on one from 79 and you say 80. ✓
Watch out. Do not write 79 again. The answer is the next number.
Method. Start with the tens, then add the ones.
- Write 5 tens. The tens go on the left.5 tens = 50
- Add 6 ones. The ones go on the right, after the tens.50 + 6 = 56
- Write the number. 56
Check. Read it back: 56 has 5 tens and 6 ones. ✓
Watch out. The tens digit goes on the left. Write 5 tens and 6 ones as 56, not 65.
Key words. A ten is a bundle of ten ones. A one is a single thing.
Method. Count the groups of ten first. Then count the ones left over.
- Count the tens in 38. Each group of ten is one ten.30 is 3 tens
- Count the ones left over. The ones are what is left after the tens.38 − 30 = 8 ones
- Write the answer. 3 tens and 8 ones
Check. Put them back together: 30 + 8 = 38. ✓
Watch out. The tens come first when you say the number. 25 is 2 tens and 5 ones, not 5 tens and 2 ones.
Method. Each number is 10 more than the one before it.
- Look at the numbers around each gap. The numbers go up or down by the same amount each time.20, 30, ?, 50
- Work out each missing number. Use the number before the gap, and add 10.Gap 3: 30 + 10 = 40
- Write the missing numbers. 40
Check. Read the whole line again. Every number is 10 more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go on by the same amount.
Method. 10 less means one row up on the 100 square. Only the tens change.
- Find 64. 64 is 6 tens and 4 ones.64 = 6 tens and 4 ones
- Change the tens. Take away one ten. The ones stay the same.5 tens and 4 ones
- Write the answer. 54
Check. 64 − 10 = 54. ✓
Watch out. Only the tens change. 64 becomes 54, not 63.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.61: 6 tens 16: 1 tens
- Compare the tens. The number with more tens is the bigger number.6 tens is more than 1 tens
- Write the answer. Bigger means more.61
Check. On the 100 square, 61 is further along than 16. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.
Key words. To count back is to say the numbers before, one less each time.
Method. Start at 40. Say the number before it, then the one before that.
- Start at 40. Put your finger on the number you start from.Start: 40
- Say 5 numbers, going back. Each number is one less than the one before.39, 38, 37, 36, 35
- Write the numbers in order. Write each number you said.39, 38, 37, 36, 35
Check. Count on from 35 to 40 to check. The same numbers come again. ✓
Watch out. Do not say 40 again. Start with the number just before it.
Method. Each number is 1 more than the one before it.
- Look at the numbers around each gap. The numbers go up or down by the same amount each time.96, 97, ?, 99, 100
- Work out each missing number. Use the number before the gap, and add 1.Gap 3: 97 + 1 = 98
- Write the missing numbers. 98
Check. Read the whole line again. Every number is 1 more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go on by the same amount.
Key words. A ten is a bundle of ten ones. A one is a single thing.
Method. Count the groups of ten first. Then count the ones left over.
- Count the tens in 60. Each group of ten is one ten.60 is 6 tens
- Count the ones left over. The ones are what is left after the tens.60 − 60 = 0 ones
- Write the answer. 6 tens and 0 ones
Check. Put them back together: 60 + 0 = 60. ✓
Watch out. The tens come first when you say the number. 25 is 2 tens and 5 ones, not 5 tens and 2 ones.
Key words. Bigger means more. Smaller means less.
Method. Compare the tens first. Only compare the ones if the tens are the same.
- Look at the tens of each number. The tens tell us the big part of the number.Leo: 3 tens Aisha: 2 tens
- Compare the tens. The number with more tens is the bigger number.3 tens is more than 2 tens
- Write the answer. Bigger means more.Leo
Check. On the 100 square, 30 is further along than 25. ✓
Watch out. A number with more ones is not always bigger. Compare the tens first.