Shannon's number or how many different chess games can be played

In 1950, the American mathematician Claude Shannon calculated how many non-repeating chess games exist. The number turned out to be huge, it is approximately 10 to the 118th power, and the calculation itself is described in the work "Programming a Computer for Playing Chess".

In order to understand how many times one can play chess in different ways, Shannon took as a basis the fact that an average chess game lasts 40 moves, and each move has about 30 variations. It turned out (10 + 10 + 10) to the 40th degree, minus some positions that are prohibited by the rules of the game. The number was named, the name of the scientist - the Shannon number, and became the first fundamental mathematical research in chess theory.

For comparison, the number of atoms in the universe is only 10 to the 80th power, and the famous googol number that gave the name to the famous Google search engine is 10 to the power of 100.