Step-by-step Maths Level 2: One more, one less, ten more and ten less
Part of the Step-by-step Maths Level 2 comparing and ordering to 100 chapter. Chapter overview · whole chapter on one page
One more, one less, ten more and ten less
To find 1 more, count on one. To find 1 less, count back one.
To find 10 more, the tens digit goes up by one. To find 10 less, the tens digit goes down by one.
Key ideas
- 10 more is one more ten.
- 10 less is one less ten.
- The ones digit stays the same when you add or take away ten.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.47
- Change it. Add ten. The tens digit goes up by one.47 + 10 = 57
- Write the answer. 57
Check. Reverse the change: 57 - 10 gives 47.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.83
- Change it. Take away ten. The tens digit goes down by one.83 - 10 = 73
- Write the answer. 73
Check. Reverse the change: 73 + 10 gives 83.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.59
- Change it. Add one. Count on to the next number.59 + 1 = 60
- Write the answer. 60
Check. Reverse the change: 60 - 1 gives 59.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Watch out
Watch out. 10 more than 47 is 57, not 48. Ten more changes the tens.
Exam tip
Grown-up tip. Use a hundred square. Ask the child to move down one row for 10 more and up one row for 10 less.
Exercise 3D Practice: one more, ten more and less
Non-calculatorMethod. Change the number by the amount in the question.
- Start with the number. It is the number we change.70
- Change it. Take away one. Count back to the number before.70 - 1 = 69
- Write the answer. 69
Check. Reverse the change: 69 + 1 gives 70.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.3
- Change it. Add ten. The tens digit goes up by one.3 + 10 = 13
- Write the answer. 13
Check. Reverse the change: 13 - 10 gives 3.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.76
- Change it. Take away ten. The tens digit goes down by one.76 - 10 = 66
- Write the answer. 66
Check. Reverse the change: 66 + 10 gives 76.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.87
- Change it. Take away ten. The tens digit goes down by one.87 - 10 = 77
- Write the answer. 77
Check. Reverse the change: 77 + 10 gives 87.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.73
- Change it. Add ten. The tens digit goes up by one.73 + 10 = 83
- Write the answer. 83
Check. Reverse the change: 83 - 10 gives 73.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.43
- Change it. Add ten. The tens digit goes up by one.43 + 10 = 53
- Write the answer. 53
Check. Reverse the change: 53 - 10 gives 43.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.79
- Change it. Add ten. The tens digit goes up by one.79 + 10 = 89
- Write the answer. 89
Check. Reverse the change: 89 - 10 gives 79.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.71
- Change it. Take away ten. The tens digit goes down by one.71 - 10 = 61
- Write the answer. 61
Check. Reverse the change: 61 + 10 gives 71.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.20
- Change it. Take away one. Count back to the number before.20 - 1 = 19
- Write the answer. 19
Check. Reverse the change: 19 + 1 gives 20.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.47
- Change it. Add ten. The tens digit goes up by one.47 + 10 = 57
- Write the answer. 57
Check. Reverse the change: 57 - 10 gives 47.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.99
- Change it. Take away one. Count back to the number before.99 - 1 = 98
- Write the answer. 98
Check. Reverse the change: 98 + 1 gives 99.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.17
- Change it. Add one. Count on to the next number.17 + 1 = 18
- Write the answer. 18
Check. Reverse the change: 18 - 1 gives 17.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.39
- Change it. Take away one. Count back to the number before.39 - 1 = 38
- Write the answer. 38
Check. Reverse the change: 38 + 1 gives 39.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.40
- Change it. Add one. Count on to the next number.40 + 1 = 41
- Write the answer. 41
Check. Reverse the change: 41 - 1 gives 40.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.75
- Change it. Add ten. The tens digit goes up by one.75 + 10 = 85
- Write the answer. 85
Check. Reverse the change: 85 - 10 gives 75.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.50
- Change it. Take away one. Count back to the number before.50 - 1 = 49
- Write the answer. 49
Check. Reverse the change: 49 + 1 gives 50.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.