Let $\displaystyle n \in \mathbb{Z}$ be an integer with $\displaystyle n \ge 0$. State and prove the contrapositive of the

following statement: If $\displaystyle n^2$ is an odd number, then n is odd.

I can prove this by substituting n for 2m and proving $\displaystyle n^2$ is even. but am unsure if this is the final extent to what i need to proof, how far do i need to go to prove this, should i give more examples?