Correct
Explanation
Between 1 and 100, the digit 9 occurs in 9, 19, 29, 39, 49, 59, 69, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 and 99.
Solve this puzzle
Which scientist developed his theories of black holes in the 1970s?