Question

Which numbers in the following set are prime numbers: (4,7,31, 117, 324)?

Answer 1

`7` and `31` are prime numbers.

Explanation:

A prime number is a natural number greater than 1 which is only divisible by `1` and itself.

From the set `4` and `324` cannot be prime, because they are even.

The remaining numbers are `7,31` and `117`

`117` can be written as `117=3xx39=3xx3xx13=3^2xx13`, so it is also not a prime number.

Remaining numbers are `7` and `31` and they are prime numbers.