Mathematical induction

So I have to prove, by mathematical induction, that 2^n <= n! for every positive integer where n >= 4.

However, while I do understand the basics of induction, I haven't a clue how to work with factorial numbers.

Any (preferably elaborate) tips? :3

n^2 <== n! for n = 4 (16<= 24)
Then assume n^2 <= n! for n = k
(k+1)^2 = k^2 + 2k +1 =< k! + 2k + 1 =< k! +k*k! (I'm sure you can justify this yourself) = (k+1)!

so it follows