Write 63 as a product of prime factors

prime factors are prime numbers that are factors of the given number. the given number should be divisible by its factors.
to find the prime factors of 63, we have to keep dividing 63 by divisible prime numbers.                                                                           
63 / 3 = 21                                                                                                                                                                                                             21 / 3 = 7                                                                                                                                                         7 / 7 = 1                                                                                                                                                      63 was divided by 3, 3 and 7 which are all prime numbers.
therefore 63 as a product of prime numbers are 63 = 3 x 3 x 7