According to legend, a Chinese Emperor asked a sage what reward he would require in return for an important service.
The sage named his price: nothing more than some rice, two grains to be placed on the first square of a chessboard, four on the second, eight on the third, and so on.
A modest demand, the Emperor thought, and happily agreed; but he had failed to grasp the principle of geometric progressions.
The entire rice crop of the empire would have had to go on a single square, long before the sixty fourth was reached.