How many times is 1 used on a 100 grid?

In a 100-grid (a 10x10 grid where each cell represents a number from 1 to 100), the digit '1' appears in various positions. It shows up once in the numbers 1 through 9, ten times in the tens place for 10 to 19, and once in 21, 31, 41, 51, 61, 71, 81, 91. In total, '1' appears 21 times in the grid.