20
There are 11, 6's in 1-1006,16,26,36,46,56,66,76,86,96
20
20
There are 20 6's
20 if you count 66 twice 19 if not
11
20
20
10
19
If you count from 1 to 100 you pass 11 6's along the way: 6, 16, 26, 36, 46, 56, 66, 76, 86, and 96.
Count them up. 6, 16, 26 ... 96 60, 61, 62 ...