find the limit of $\displaystyle n^2*e^{-n}$ as n approaches infinity

I just dont see how to do limits of more complex things. I can take each part by itself, find its limit and multiply them by algebra rules of limits. But n^2 = infinity and e^-n = 0. That does not work. L'Hop rule does not work either.

I am really confused on how to do limits.