In this activity, we will carry out addition and subtraction of negative numbers.
It is really important to learn the rule for negative numbers, so let's recap it here.
When two signs are written next to each other:
If the two signs are different, they make a negative sign.
If the two signs are the same, they make a positive sign.
This means that:
+ and - make a negative
- and + make a negative
+ and + make a positive
- and - make a positive
For example, when adding a negative number, you have + and - together, so the answer will be negative:
7 + -9 = 7 - 9 = -2
When subtracting a negative number, you have - and - together, so the answer will be positive:
3 - -5 = 3 + 5 = 8
Let's have a go at some questions.