Question

The question is "13, 17, 21, 23, 29 one of the numbers is different from the rest, which one and why?"

step by step explanation

Answer 1

21

Explanation:

it is not a prime number, according to prime number only the number and 1 can it be divided but here 21 can be divided by 1,3,7 and 21 itself. Therefore others are prime number except 21