Hi Peter,

Let's try to think of the problem in a different way. We want a number when it divides 90 it leaves a remainder of 10 or in other words, we want a number that will divide evenly into 80 (10 less than 90). Since the remainder is 10, we know that the divisor is greater than 10. Find a list of all the numbers that divide evenly into 80 and the smallest number that is greater than 10 but is not a divisor of 90 will be your answer.

Hope this hint helps you out
Janice