## Why is this formula true?

We have a set of $n$ elements. We would like to assign them to $k$ sub-sets, so that each sub-set has $m$ elements. The number of all possible assignments is then $\frac{n!}{k!(m!)^k}$.

Can someone help me intuit this formula?

EDIT: I intuit the $k!$ in the denominator, but not the rest.

EDIT2: Crap, I've got it ... writing it down somehow helps.