Question

Which number is prime? 10 5 15 18​

Answer 1

5

Explanation:

Prime numbers: 2,3,5,7,11,13,17,19 and so on, and 5 is the only one.

10 is a multiple of 5 and 2, 15 is a multiple of 5 and 3, 18 are multiples of 2,3,6,9.