I know several have answered it, but here is how you do it. Break the answer 104 into its prime numbers.

104
2 52
2 26
2 13
13 1


So the prime numbers that make the answer are 2, 2, 2, and 13. At some point you will have to use some product of these numbers to get your answer. It's all intuitive manipulation after you break down the number into its base parts.

BG