Visual Math proofs

1 + 3 + 5 + ... + (2n − 1) = n * n

I have always loved visual math proofs like these. The one above proves that the sum of 2n - 1 for any integers ranging from 1 to n is n squared. I think it is very important to understand that problems that seem hard under one representation may seem very easy if they are represented another way: sometimes we can solve problems just by changing the way we look at them.