How many numbers are there between 1 to 100 which have the digit 1?

There are 20 numbers between 1 and 100 that contain the digit '1'. These numbers are: 1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 31, 41, 51, 61, 71, 81, 91, and 100.