# What is meant by “m|n”? Two letters separated by a vertical bar (|)

I am new to this subject, and not not sure what "|" symbol means on this statement.

Let $R_2 \subset\Bbb N \times\Bbb N$ be defined by $(m, n) \in R_2$ if and only if $m|n$.

-
$m$ divides $n$. –  Sami Ben Romdhane Jul 24 '14 at 19:33
@SamiBenRomdhane: that is a full answer –  Ross Millikan Jul 24 '14 at 19:35
Note that by the relation's definition, $\: 0 \hspace{.03 in} | \hspace{.03 in} 0 \:$ is true. $\;\;\;$ –  Ricky Demer Jul 25 '14 at 4:12

$m \mid n$ means that $m$ divides $n$.
We could also say that $n$ is divisible by $m$ AND we could also say that $n$ is a multiple of $m$,so $n= a \cdot m, a \in \mathbb{Z}$.