Answer
There are 65 pages, and the number 9 appears six times.
Reasoning
The first 9 pages each require one digit per page, which leaves 112 digits remaining. This requires an additional 112 ÷ 2 = 56 more pages. For a total of 9 + 56 = 65 pages.
Each block of ten contains a single 9, for a total of six 9's (as we've only reached page 65, and we don't have to worry about the 9's in the 90's either).
Double-Checking
The 65 pages are (with the six 9's highlighted):
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65.
If we remove the spaces, we get:
1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465. Which is 121 digits.
