In the top row of an 8*8 chessboard, Tom writes the values 1, 2, 4, 8, 16, 32, 64, 128. In the leftmost column, Tom writes the values 1, 3, 9, 27, 81, 243, 729, 2187. In every other square that doesn't have a number yet, Tom writes the product of the leftmost number in that square's row and the topmost number in that square's column. What is the sum of all the numbers on the chessboard?

Answer 1

Do it yourself

Answer 2

So here is the 8x8 chessboard with the given info filled in
1 2 4 8 16 32 64 128
3
9
27
81
243
729
2187

Add up the first row, you get 255. (1+2+4+...+128)
If you multiply out the second row and add it up, it equals 765. (3+6+12+...+384)
Notice that 255*3=768
This pattern continues on for the other rows, and you can probably solve it from here

Answer 3

EDIT: 255*3=765
sorry typo :P