How many prime numbers are there between 1 and 15?

2,3,5,7,11,13 -- There seem to be 6 of them.

A prime is a number other that 1 which has not factors except itself and 1.

4 = 2* 2 , so not prime

6 = 2* 3 , so not prime ( In fact 2 is a factor of every even number, so no even numbers but 2 itself are prime.)

9 = 3*3, so not prime

15 = 3*5, so not prime