The king, impressed by the game, asked the mathematician to name his reward.

The mathematician asked for grains of wheat, using the chessboard to calculate the amount. He requested that a single grain of wheat be placed on the first square and doubled for every subsequent square.

This means two grains on the second square, four on the third, eight on the fourth, and so on, for all 64 squares on the chessboard.

Initially, the request seemed modest to the king, who agreed.

However, the reality of exponential growth became apparent as the process unfolded.

By the time the board was half-covered (at the 32nd square), the number of grains was already enormous, reaching over four billion. As the squares continued to be filled, the numbers grew astronomically larger.

By the 64th square, the total wheat needed for the entire board reached 18,446,744,073,709,551,615 grains—about 18.4 quintillion.

To put this into context, let's convert this to a more understandable measure, such as metric tons. The average weight of a grain of wheat is about 50 milligrams or 0.00005 kilograms.

18,446,744,073,709,551,615 grains * 0.00005 kilograms/grain = 922 trillion kilograms.

Since there are 1,000 kilograms in a metric ton, this equals about 922 billion metric tons.

To compare this with global wheat production, let's consider recent figures. According to the Food and Agriculture Organization of the United Nations, the world's wheat production in a recent year was about 761 million metric tons.