11 times
19 times.
300
24 times
19 7, 17, 27, 37,47, 57, 67, 77, 87, 97 70, 71, 72, 73, 74, 75, 76, 78, 79
As a digit in other numbers it appears 20 times
Infinitely many.
18
200
200
16
It appears 25 times.
A total of 44 times.
18 times
20000 times
700000
If 11 and 111 is counted as 1 digit, the answer is 119.If 11 is counted as 2 digit 1's, the answer is 131.