primes.rb

# require 'Math'

def is_prime?(num)
  (2..Math.sqrt(num)).each { |factor| return false if num % factor == 0 }
  true
end

def prime_factors(num)
  primes_hash = {}
  primes = []

  #Setting up hash of prime factors
  (2..Math.sqrt(num)).each do |factor|
    primes_hash[factor] = (num % factor == 0) if is_prime?(factor)
  end 

  # Looking in primes hash for potential factors
  primes_hash.each do |factor, is_multiple|
    primes << factor if is_multiple
  end

  primes 
end

puts prime_factors(3).inspect         # => [3]
puts prime_factors(6).inspect         # => [2,3]
puts prime_factors(8).inspect         # => [2,2,2]
puts prime_factors(25).inspect        # => [5,5]
puts prime_factors(123123123).inspect # => [3, 3, 41, 333667]