[Exercism.io] Prime Factorization Code

gistfile1.rb

## Prime Factor Storm
## Demannu 9/29/2014
# 3 -> Pling
# 5 -> Plang
# 7 -> Plong
# If factors aren't 3,5,7 just display the number
require 'mathn'
class Raindrops
	def self.convert(toFactor)
		primeNumbers = [2, 3, 5, 7, 9]
		primeFactors = []
		raindropString = ""
		factors = toFactor.prime_division
		factors.each do |factor|
			case factor
			when 3
				raindropString = raindropString.concat("Pling")
			when 5
				raindropString = raindropString.concat("Plang")
			when 7
				raindropString = raindropString.concat("Plong")
			else 
				raindropString = toFactor
			end			
		end
		puts raindropString
	end
end

# Issue is when you run this, no matter the number it returns nil