My number has a tens digit that is 8 more than the ones digit. Zero is not one of my digits

If the number only has 2 digits, it could only be 91, because since the tens digit is 8 more than the ones digit, the tens digit is greater than or equal to 8. it cannot be 10 or more, because that would make the number over 100, leaving only 8 and 9. If the tens digit is 8, the ones digit is zero, and since it cannot be zero, then the tens digit must be 9, leaving the ones digit to be 1. So, the final answer is 91.