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Ashta’s chess tales

払えなかった王さま

India, a very old legend · 2 minute read

王さまが笑ったほど小さなほうび — けれど、王国でも払えないほど大きなほうびでした。

This is a legend, and nobody knows how much of it is true. But it has been told for about a thousand years, so it has earned its place.

A king, the story goes, was bored with every game in his palace. A wise man the stories call Sissa brought him a new one: a board of sixty-four squares and two small armies. The king played all night. In the morning he said, “Name your reward.”

“Only rice,” said the wise man. “One grain on the first square. Two on the second. Four on the third. Double it on every square until the board is full.”

The king laughed at so small a wish and sent for a sack. By the end of the first row the servants had laid down 255 grains. By the end of the second row, more than 65,000. Somewhere in the fourth row the palace granary was empty, and there were still thirty-two squares to go.

The full board needs 18,446,744,073,709,551,615 grains. That is more rice than the whole world grows in hundreds of years.

Some tellers say the king was angry. Others say he was delighted, because the wise man had taught him two things in one day: a game, and how fast a number grows when you keep doubling it.