To find a prime number you need to know that a prime number have 2 factors which is 1 and the number itself in other words if the answer has a decimal when divided then it's a prime number for example:
70 divided by 5 is > 14 < no decimal then it is not prime
71 divided by 71 is 1
and 1 divided by 71 is 1 so if every answer has the only factor which is 1 and itself then it is a prime number
