Question

Here are some numbers:
4
6 7
15
21
Which number is a prime number?

Answer 1

67

Explanation:

all prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199,

Answer 2

7

Explanation:

Prime numbers have a factor of 1 and itself.

4 is not prime because it has a factor of 2.

6 is not prime because it has factors 2 and 3.

7 is prime, it has 1 and 7 as its factors.

15 is not prime, it has factors of 3 and 5.

21 is not prime, it has factors of 3 and 7.

The only prime number from the list is 7, because the only factors it has is 1 and itself.