Compensate

The idea behind this strategy is to take one of the numbers in the subtraction up to its nearest ten. Next, do the subtraction. Then, add the difference back on.

For example, work out the subtraction 45 minus 28. First, add 2 to 28 to make it 30. Next, take 30 from 45 to leave 15. Then, add the 2 back on to the 15 to make 17.

Let's try this strategy on 58 minus 29. First, add 1 to 29 to make it 30. Next, take 30 away from 58. Then, add the 1 back on.

Did you get 29 for your answer?

Another example of the compensate strategy is to compensate both numbers with the same amount. For example, let's look at the subtraction 58 minus 29. First, add 1 to 29 to make 30. Next, add 1 to 58 to make 59. Then, take 30 away from 59.

This gives the answer 29. Because the same amount has been added to each of the numbers, there is no need to add or take away anything else.