Proof that $ 1^3+2^3+\cdots +n^3 = (1+2+\cdots+n)^2$ without using induction

Question

Possible Duplicate:
Intuitive explanation for the identity $\sum\limits_{k=1}^n {k^3} = \left(\sum\limits_{k=1}^n k\right)^2$

How to prove this without using mathematical induction?

$$1^3+2^3+\cdots+n^3 = (1+2+\cdots+n)^2$$

I know how to prove it by induction, is there a different way?