Year 2: Counting in tens from any number

Method. Start at 23. Count on in tens.

1. Start at 23. Put your finger on the number you start from.
   Start: 23
2. Say each number, going on 10 each time. Each new number is 10 more than the one before.
   33, 43
3. Write the numbers in order. Write each number you said.
   33, 43

Check. Count back from 43. You reach 23. ✓

Watch out. Do not say 23 again. Start with the next number.

Method. Start at 62. Count back in tens.

1. Start at 62. Put your finger on the number you start from.
   Start: 62
2. Say each number, going back 10 each time. Each new number is 10 less than the one before.
   52, 42
3. Write the numbers in order. Write each number you said.
   52, 42

Check. Count on from 42. You reach 62. ✓

Watch out. Do not say 62 again. Start with the next number.

Method. 10 more changes only the tens digit.

1. Find 47. 47 is 4 tens and 7 ones.
   47 = 4 tens and 7 ones
2. Add one ten. The ones digit stays the same.
   4 tens + 1 ten = 5 tens and 7 ones
3. Write the answer.
   57

Check. 47 + 10 = 57. ✓

Watch out. Only the tens change. 47 becomes 57, not 48.

Method. 10 less changes only the tens digit.

1. Find 81. 81 is 8 tens and 1 one.
   81 = 8 tens and 1 one
2. Take away one ten. The ones digit stays the same.
   8 tens − 1 ten = 7 tens and 1 one
3. Write the answer.
   71

Check. 81 − 10 = 71. ✓

Watch out. Only the tens change. 81 becomes 71, not 80.

Method. 10 more changes only the tens digit.

1. Find 35. 35 is 3 tens and 5 ones.
   35 = 3 tens and 5 ones
2. Add one ten. The ones digit stays the same.
   3 tens + 1 ten = 4 tens and 5 ones
3. Write the answer.
   45

Check. 35 + 10 = 45. ✓

Watch out. Only the tens change. 35 becomes 45, not 36.

Method. The numbers go up by 10 each time.

1. Look at the numbers around each gap. Each number is 10 more than the one before it.
   16, 26, ?, 46, ?
2. Work out each missing number. Add 10 to the number before the gap.
   26 + 10 = 36
   46 + 10 = 56
3. Write the missing numbers.
   36, 56

Check. Count on in 10s 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. 10 more changes only the tens digit.

1. Find 38. 38 is 3 tens and 8 ones.
   38 = 3 tens and 8 ones
2. Add one ten. The ones digit stays the same.
   3 tens + 1 ten = 4 tens and 8 ones
3. Write the answer.
   48

Check. 38 + 10 = 48. ✓

Watch out. Only the tens change. 38 becomes 48, not 39.

Method. 10 more changes only the tens digit.

1. Find 25. 25 is 2 tens and 5 ones.
   25 = 2 tens and 5 ones
2. Add one ten. The ones digit stays the same.
   2 tens + 1 ten = 3 tens and 5 ones
3. Write the answer.
   35

Check. 25 + 10 = 35. ✓

Watch out. Only the tens change. 25 becomes 35, not 26.

Method. There are 6 groups of 10. Count in 10s to find the total.

1. Count the groups: 6. Each group has 10 pencils.
   6 groups of 10
2. Count in 10s, one group at a time. Add 10 for every group.
   10, 20, 30, 40, 50, 60
3. Write the total.
   60

Check. Count in 10s to check. The last number you say is 60. ✓

Watch out. Count in 10s, not in ones. Each group is 10.

Method. 10 more changes only the tens digit.

1. Find 49. 49 is 4 tens and 9 ones.
   49 = 4 tens and 9 ones
2. Add one ten. The ones digit stays the same.
   4 tens + 1 ten = 5 tens and 9 ones
3. Write the answer.
   59

Check. 49 + 10 = 59. ✓

Watch out. Only the tens change. 49 becomes 59, not 50.