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

1 Answer
Dec 16, 2016

#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.