Year 2 Place value to 100: check-up and quiz

Method. Start at 10. Count on in twos.

1. Start at 10. Put your finger on the number you start from.
   Start: 10
2. Say each number, going on 2 each time. Each new number is 2 more than the one before.
   12, 14, 16
3. Write the numbers in order. Write each number you said.
   12, 14, 16

Check. Count back from 16. You reach 10. ✓

Watch out. Do not say 10 again. Start with the next number.

Method. The numbers go up by 5 each time.

1. Look at the numbers around each gap. Each number is 5 more than the one before it.
   15, 20, ?, 30
2. Work out each missing number. Add 5 to the number before the gap.
   20 + 5 = 25
3. Write the missing numbers.
   25

Check. Count on in 5s through the whole line. It works. ✓

Watch out. Check the numbers after the gap too. They should still go up by the same step.

Method. Start at 46. Count on in tens.

1. Start at 46. Put your finger on the number you start from.
   Start: 46
2. Say each number, going on 10 each time. Each new number is 10 more than the one before.
   56, 66
3. Write the numbers in order. Write each number you said.
   56, 66

Check. Count back from 66. You reach 46. ✓

Watch out. Do not say 46 again. Start with the next number.

Method. 10 less changes only the tens digit.

1. Find 73. 73 is 7 tens and 3 ones.
   73 = 7 tens and 3 ones
2. Take away one ten. The ones digit stays the same.
   7 tens − 1 ten = 6 tens and 3 ones
3. Write the answer.
   63

Check. 73 − 10 = 63. ✓

Watch out. Only the tens change. 73 becomes 63, not 72.

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.

1. Count the tens in 68. Each group of ten is one ten.
   60 is 6 tens
2. Count the ones left over. The ones are what is left after the tens.
   68 − 60 = 8 ones
3. Write the answer.
   6 tens and 8 ones

Check. Put them back together: 60 + 8 = 68. ✓

Watch out. The tens come first when you say the number. 25 is 2 tens and 5 ones.

Key words. The value of a digit is how much it is worth.

Method. The place of a digit tells us what it is worth.

1. Find the tens digit in 53. The tens digit is on the left.
   The tens digit is 5
2. Work out what 5 tens is worth. 5 tens means 5 groups of ten.
   5 tens = 50
3. Write the answer.
   50

Check. 50 + 3 = 53, so the tens and ones make 53. ✓

Watch out. The digit is not always worth what it shows. In 53, the tens digit is worth 50.

Method. Start with the tens, then add the ones.

1. Write 7 tens. The tens go on the left.
   7 tens = 70
2. Add 3 ones. The ones go on the right, after the tens.
   70 + 3 = 73
3. 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.

Key words. A numeral is a number written with digits, like 36. Words are written out, like thirty-six.

Method. Say the number out loud, then write the words for it.

1. Split the number into tens and ones. The tens come first, then the ones.
   84 = 8 tens and 4 ones
2. Write the tens word. 8 tens is written as eighty.
   eighty
3. Add the ones word after a hyphen. A hyphen joins the tens word and the ones word.
   eighty-four

Check. Read it back: eighty-four is 84. ✓

Watch out. Put a hyphen between the tens word and the ones word, like thirty-six.

Key words. < means less than. > means more than. = means equal to.

Method. Compare the tens first. Only look at the ones if the tens are the same.

1. Look at the tens of each number. The tens tell us the big part of each number.
   39: 3 tens   93: 9 tens
2. Compare the tens. More tens means a bigger number.
   9 tens is more than 3 tens
3. Write the sign. The point of the sign faces the smaller number.
   39 < 93

Check. Read it out loud: 39 is less than 93. ✓

Watch out. A number with more ones is not always bigger. Look at 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.

1. Look at the tens of each number. A number with fewer tens is smaller.
   64: 6 tens   46: 4 tens   56: 5 tens
2. Put them in order, smallest first. Start with the smallest number, then the next one.
   46, 56, 64
3. Write the answer.
   46, 56, 64

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.

Method. Start at 6. Count on in twos.

1. Start at 6. Put your finger on the number you start from.
   Start: 6
2. Say each number, going on 2 each time. Each new number is 2 more than the one before.
   8, 10, 12, 14
3. Write the numbers in order. Write each number you said.
   8, 10, 12, 14

Check. Count back from 14. You reach 6. ✓

Watch out. Do not say 6 again. Start with the next number.

Method. There are 5 groups of 2. Count in 2s to find the total.

1. Count the groups: 5. Each group has 2 socks.
   5 groups of 2
2. Count in 2s, one group at a time. Add 2 for every group.
   2, 4, 6, 8, 10
3. Write the total.
   10

Check. Count in 2s to check. The last number you say is 10. ✓

Watch out. Count in 2s, not in ones. Each group is 2.

Method. Start at 21. Count back in threes.

1. Start at 21. Put your finger on the number you start from.
   Start: 21
2. Say each number, going back 3 each time. Each new number is 3 less than the one before.
   18, 15, 12
3. Write the numbers in order. Write each number you said.
   18, 15, 12

Check. Count on from 12. You reach 21. ✓

Watch out. Do not say 21 again. Start with the next number.

Method. Start at 27. Count on in tens.

1. Start at 27. Put your finger on the number you start from.
   Start: 27
2. Say each number, going on 10 each time. Each new number is 10 more than the one before.
   37, 47
3. Write the numbers in order. Write each number you said.
   37, 47

Check. Count back from 47. You reach 27. ✓

Watch out. Do not say 27 again. Start with the next number.

Method. 10 more changes only the tens digit.

1. Find 84. 84 is 8 tens and 4 ones.
   84 = 8 tens and 4 ones
2. Add one ten. The ones digit stays the same.
   8 tens + 1 ten = 9 tens and 4 ones
3. Write the answer.
   94

Check. 84 + 10 = 94. ✓

Watch out. Only the tens change. 84 becomes 94, not 85.

Method. Start with the tens, then add the ones.

1. Write 9 tens. The tens go on the left.
   9 tens = 90
2. Add 1 one. The ones go on the right, after the tens.
   90 + 1 = 91
3. Write the number.
   91

Check. Read it back: 91 has 9 tens and 1 one. ✓

Watch out. The tens digit goes on the left. Write 9 tens and 1 one as 91.

Key words. The value of a digit is how much it is worth.

Method. The place of a digit tells us what it is worth.

1. Find the tens digit in 84. The tens digit is on the left.
   The tens digit is 8
2. Work out what 8 tens is worth. 8 tens means 8 groups of ten.
   8 tens = 80
3. Write the answer.
   80

Check. 80 + 4 = 84, so the tens and ones make 84. ✓

Watch out. The digit is not always worth what it shows. In 84, the tens digit is worth 80.

Method. Break the word into a tens word and a ones word.

1. Find the tens word. forty means 4 tens.
   forty = 40
2. Find the ones word. The ones word comes after the hyphen.
   five = 5
3. Add the tens and the ones. Put the tens and the ones together.
   40 + 5 = 45
4. Write the answer.
   45

Check. Say the number: forty-five is 45. ✓

Watch out. The tens word comes first, like thirty in thirty-six.

Key words. < means less than. > means more than. = means equal to.

Method. Compare the tens first. Only look at the ones if the tens are the same.

1. Look at the tens of each number. The tens tell us the big part of each number.
   58: 5 tens   85: 8 tens
2. Compare the tens. More tens means a bigger number.
   8 tens is more than 5 tens
3. Write the sign. The point of the sign faces the smaller number.
   58 < 85

Check. Read it out loud: 58 is less than 85. ✓

Watch out. A number with more ones is not always bigger. Look at the tens first.

Method. Find which ten is closer by counting the steps to each ten.

1. Find the two tens either side of 36. 36 is between 30 and 40.
   30 and 40
2. Count the steps to each ten. Count how far it is to each ten.
   36 to 30: 6 steps   36 to 40: 4 steps
3. Pick the closer ten. The ten with fewer steps is closer.
   40

Check. 40 is closer, with 4 steps. ✓

Watch out. Count the steps to both tens. Do not just guess.