Question

I am thinking of a number it's less than 20 it's an odd number it's got 2 different prime factors what number am I thinking of

Answer 1

This is a real tricky question. There are a lot of primes that fit this description.

3 5 7 9 (does't work. It's prime factors are the same).
11 13 17 19

I think the answer you want is 15, but it depends on what you have been told about 1. Is 1 prime or not?