Question

What are the prime factors of $90$?

Answer 1

First, because 90 is an even number we can factor out a 2:

90 = 2 × 45

Because 45 ends in a 5 it is divisible by 5 so we can factor out a 5:

90 = 2 × 5 × 9

We know 9 is divisible by 3 so we can factor our a 3:

90 = 2 × 5 × 3 × 3

Or

90 = 2 × 3 × 3 × 5

So,2,3 and 5 are prime factors of 90