According to legend, chess was invented by Grand Vizier Sissa Ben Dahir, and given as a gift to King Shirham of India. The king was so delighted that he offered him any reward he requested, provided that it sounded reasonable. The Grand Vizier requested the following: "Just one grain of wheat on the first square of a chessboard. Then put two on the second square, four on the next, then eight, and continue, doubling the number of grains on each successive square, until every square on the chessboard is reached."
Intuitively, King Shirham — just like almost anybody else — underestimated the number of grains and laughed at Sissa because he had asked such a small gift. When he had someone to calculate the total number of grains, it took more than a week before he came back with the solution. King Shirham undoubtedly became very pale when he got the answer: the aggregated number of grains on all squares of a chessboard would be 18.446.744.073.709.551.615 grains. This is the harvest of all the wheat of the world, of several decades.