An even number is any integer that is divisible exactly by $2.$ In other words, an even number is a multiple of $2.$ If an integer $n$ is divided by $2$ and the result $k$ is an integer, then $n$ is an even number.

$n$	$\frac{n}{2}$	$k$	Even?
$\text{-}4$	$\frac{\text{-}4}{2}$	$\text{-}2$	Yes
$3$	$\frac{3}{2}$	$1.5$	No
$18$	$\frac{36}{2}$	$9$	Yes
$25$	$\frac{25}{2}$	$12.5$	No

Even numbers are usually defined as numbers $n$ that can be written in the form $n=2k,$ where $k$ is an integer.