What are the prime factors of 45?

##1, 3, 5##

factors of ##45##

##45times1## ##9times5## ##15times3##

A prime factor is a prime number. A prime number can only be divided by ##1## or itself.

##45## can still be factored into ##9times5## so it is not prime. ##9## can still be factored into ##3times3## so it is not prime. ##15## can still be factored into ##5times3## so it is not prime.

So only ##1,3, 5## are prime because their only factors are ##1## and the number itself.