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Read the following text and answer the questions to it.
The Game of Chess
You will probably know that the game of chess so popular nowadays all over the world comes from India. According to an old legend it was invented by king Shirham's vizier Sissa Ben Dahir and presented to the king by the latter. The King was very pleased and asked Sissa Ben whether he could do anything to thank him for the present. His vizier's desire seemed quite easy to fulfil. He asked his king to give him a grain of wheat to put on the first square of the chessboard, and two grains to put on the second square, and four grains to put on the third square and eight grains to put on the fourth and so on doubling the number for each square that came next. He said he wanted the grains to cover all 64 squares of the board.
The king thought his vizier did not ask too much for what he-had done and said that he would certainly give him what he asked for.
And he told his men to bring a large bag full of wheat.
But when the counting began, with 1 grain for the first square, 2 for the second, 4 for the third and so on the bag was emptied before the twentieth square was covered with wheat. More bags were brought before the king but the number of grains needed increased so rapidly that the king soon saw he would not be able to keep his word.
The thing is that a bushel of wheat contains about 5,000,000 grains. The king had, certainly, no idea of it and did not expect that he would have to give 4000 billion bushels to Sissa Ben.
Since the world production of wheat averages about 2,000,000,000 bushels a year, the amount of wheat asked by the vizier equalled the world's wheat production for the period of some two thousand years.
Thus king Shirham found that he either had to remain constantly in debt to his vizier or cut his head off. He thought it best to choose the latter alternative.