Here's the old chessboard problem, dunno if anyone's posted it yet.
The man who invented the chessboard goes to the king and delivers it and says, I would like 1 grain of rice for each tile but doubling each time, (8x8 Chessboard) so he starts with 1 grain of rice fro the first, 2 for the second, 4 for the 3rd, 8 for the 4th, 16 for the 5th, 32 for the 6th..... n amount for nth term. How much rice does the man get all together?