square is an operation. for example, the square of a means a×a, abbreviated as a², or it can also be written as a×a (a to the first power × a to the first power = a to the second power), for example, 4×4=16 , 8×8=64, the square sign is 2. that is, 2 squared is 4, which is equal to 2×2=4.

according to legend, a minister in india invented chess and dedicated it to the king. the king was very grateful and agreed to fulfill his request: put rice grains on the chessboard. place 1 grain in the first square, 2 grains in the second square, then 4 grains, 8 grains, 16 grains... until it is placed in the 64th square.

the king laughed and thought he was stupid for thinking that he only needed such a little rice.

is this really the case? according to the minister's request, to fill 64 grids, 1+2+2 meters are required.²+2³+…+2⁶³=2⁶⁴-1 capsule. this number is 18,446,744,073,709,551,615, which is a twenty-digit number. not to mention emptying the national treasury, the rice in the whole of india and even the world cannot meet the requirements of this minister!