Let $n$, $m\in\N$. We say
- $n$ divides $m$,
- or $n$ is a divisor / factor of $m$,
- or $m$ is a multiple of $n$,
- or $m$ is divisible by $n$,
written $n\divides m$, if there exists $k\in\N$ such that $m=kn$.
- $0\divides n$ for all $n\in\N$.
- $n\not\divides 0$ for all $n\in\N^+$.