How many times does the digit 9 appear in the list of all integers from 1 to 600?
From 1 to 9 = 1 time
From 10 to 99 =19 times
From 100 to 600 =20 x 5 =100 times
1 + 19 + 100 =120 times between 1 and 600
Note: This counts repeated 9's such as 99, 199....etc.
Hint:
From 1-89 - nine "9"s
From 90-99 - eleven "9"s
Try using this for the three digit numbers