posted by karen .
i am thinking of a number between 20 and 50. it is an even number. it has exactly 9 factors. what is the number?
If it has exactly 9 factors, it must be a perfect square, as only perfect squares have an odd number of factors (including 1 and the number itself).
Between 20 and 50, there are 3 perfect squares, only one of which has more than three factors.
Post if further help is required.