How do you teach someone to determine prime numbers when they don't know multiplication facts?

Do they know how to divide?

If so, tell them to divide the number in as many ways until you go past the number

For example, if your seeing if 9 is a prime number divide 9 by ,1,2,3,4,5,6,7,8,9 and only count the whole numbers.

This sounds complicated so just teach them simple time tables