Write
45
as a product of prime factors.

First, we determine the factors of 45. We can immediately note that 45 is the product of 9 and 5. Out of 9 and 5, 9 can further be expressed into the product of 3 and 3. The prime factorization therefore is,
            45 = 3 x 3 x 5
 Since the factors in the right-hand side of the equation are already prime numbers then, this factorization can no longer be written in simpler forms.