I found this problem on mathworld.com. It is a classic problem so I am hoping some body here must have seen it before. Consider a checkerboard with 64 squares. If you put 1 penny on the first box, 2 pannies on the second box, 4 pennies on the third one and continue to do this until you fill the whole checker board. How much total money you need to fill all 64 boxes? I find it to be 1.84 X 10^5 trillion dollars! How much total money is needed to fill only 32 squares? my answer: 42.9 million I just want to know if these numbers seems reasonable. Thanks, Gamma.