Question 366367
I can eliminate 70, 100, 99, and 98, which all have divisors
So I'm left with 71 through 97
I can eliminate all numbers ending in 2,4,5,6, and 8, since they
all have divisors. That leaves number ending in 1,3,7, or 9
The tens digit has to be 7,8, or 9. If the ones digit is 1 more
than the tens digit, then the possible numbers are just one: 89