What numbers between 1-100 contain only odd digits?

Answer 1

101

Answer 2

All the odd numbers of the odd tens plus the odd numbers less than 10.

There are 5 odd numbers in each ten

There are 5 odd tens, plus the numbers less than 10

giving 5 x (5+1) = 30 numbers in 1-100 (inclusive) which are comprised entirely of odd digits.

If the "between" excludes 1 and 100, then there are 29 such numbers.

Answer 3

There are 29 such numbers. Try it out.