The sum of the natural numbers a and b is found as follows: when the count reaches to a, b more numbers are counted. The number reached is the sum of a and b.

Inverse binary operation to addition is **subtraction**.

**Addition properties are**:

- commutativity - "commutative law of addition" or "commutative property of addition";
- associativity - "associative law of addition" or "associative property of addition".

**Identity element** for addition, also known as the additive identity:

$$a+0=0+a=a$$