Nine of them
10 times
9*9=81 81-9=72 72/9=88
There are: 495/9 = 55
6 of them with a remainder of 4
70 x 9 = 630
3 times with a remainder of 5
as in the multiples? 9 18 27 36 45 54 63 72 81 90 99 ...
1 goes into 81 81 times.
8, remainder 1
81 ÷ 9 = 9
9^2+9+9 +9/9 81+9+9+1=100