- Integers are closed for addition and subtraction both. That is, a + b and a – b are again integers, where a and b are any integers. - Addition is commutative for integers, i.e., a + b = b + a ...

In this KS2 Maths article you'll find out how to use mental methods when doing addition and subtraction in your head. We also have KS2 Maths videos, a quiz and lots of examples.