How many times does the number 1 appear between 1 and 100?

Answer 1

The number 1 appears once, at the beginning before the rest of the numbers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ..., 100

The digit 1 appears:

10 times in the ones column (1, 11, 21, ..., 91)

10 times in the tens column (10, 11, ..., 19)

once in the hundreds column (100)

making a total of 21 appearances.

Answer 2

The number 1 appears 21 times from 1 to 100 inclusive (number 11 counts as 2 ones).