Addition and Subtraction

Lesson

To compensate means to "pay back" or "make up a loss." How do you think this relates to the strategy of compensation?

Compensation is a strategy for addition and subtraction. It takes the answer of one problem and uses it to find the answer to another problem. To make up for the difference in the two problems, you'll need to compensate. You'll need to add or subtract an amount.

Watch this video below to see some examples where you can use compensation to help you add more easily. Do you find compensation a helpful strategy?

If $7+10=17$7+10=17, what is the answer to $7+11$7+11?

If $10-5=5$10−5=5, what is the answer to $11-5$11−5?

We want to find $88+9$88+9 by doing the following.

First, find $90+9$90+9.

How much greater will this answer be compared to the answer to $88+9$88+9?

Because the answer to $90+9$90+9 is $2$2 extra than the answer for $88+9$88+9, we can subtract $2$2 to find the final answer.

If $90+9=99$90+9=99, what is $88+9$88+9?

Use simple additive strategies with whole numbers and fractions

Generalise that whole numbers can be partitioned in many ways