## Statement

Every even number can be written as a multiple of two.

$$ 2k, \text{where} \space k \in \Z $$

## Proof

These are the even numbers:

$$ ..., -4, -2, 0, 2, 4, 6, 8, ... $$

Note that every even number is two more than the previous one.

So every even number can be written as two times a whole number $ k $.

$$ 2 * k, \text{where} \space k \in \Z $$