Method to convert numbers to their roman numeral value

roman_numeral.rb

def to_roman(num)
 roman = ""
 roman_numerals = [['M', 1000],
                  ['CM', 900],
                  ['D', 500],
                  ['CD',400],
                  ['C', 100],
                  ['XC', 90],
                  ['L', 50],
                  ['XL', 40],
                  ['X', 10],
                  ['IX', 9],
                  ['V', 5],
                  ['IV', 4],
                  ['I', 1]]
  roman_numerals.each do |numeral|
    roman << numeral[0]*(num/numeral[1])
    num = num%numeral[1] 
  end  
  return roman          
end
 

puts to_roman(1) == "I"
puts to_roman(3) == "III"
puts to_roman(6) == "VI"
puts to_roman(944)