# Prime factors of number

Finds and returns the list of prime factors of a number.

- Use a
`while`

loop to iterate over all possible prime factors, starting with`2`

. - If the current
`factor`

exactly divides`num`

, add`factor`

to the`factors`

list and divide`num`

by`factor`

. Otherwise, increment`factor`

by one.

def prime_factors(num): factors = [] factor = 2 while (num >= 2): if (num % factor == 0): factors.append(factor) num = num / factor else: factor += 1 return factors prime_factors(12) # [2,2,3] prime_factors(42) # [2,3,7]