Imagine a chessboard

suppose 1 grain of corn is placed on the first square.

2 grains on the second

4 grains on the third

8 grains on the fourth

and so on, doubling each time up to and including the 64th square.

1) How many grains would there be on the 64th square?

2) How many would there be on the nth square?

3) How many grains are there on the chessboard?