Understanding "Divides" aka "|" as used logic What are the rules for using the divides operator aka "$\mid$"? Is it false to say $2\mid5$ since $5/2$ = $2.5$ and $2.5\notin\mathbb{Z}$? Or does my question imply a misunderstanding?
I am seeing this for the first time in the 6.042J, Lecture 2: Induction on MIT OCW.
Thanks for the help.

To say that $a\ \mid\ b$, or "a divides b", is to say that $r = 0$ in the division algorithm:
$$b = qa + r.$$
