First put a square block of equal length at Line A and B, then put a square container at Line C, cut the square block into as much 1cm2 block as possible. Put those blocks into the square container at Line C. They will be fully filled in if line A and line B are natural numbers. Thus, A^2+B^2=C^2. If not, try a different number, as long as it can be divided into natural number by Line A and Line B’s square block.