Yet another version of fizz buzz kata using open classes

fizzbuzz4.rb

class Fixnum
  def divisible_by_3?
    self % 3 == 0
  end

  def divisible_by_5?
    self % 5 == 0
  end
end 
   
class FizzBuzzGame
  FIZZ = 'fizz'
  BUZZ = 'buzz'
  FIZZBUZZ = 'fizzbuzz'

  def answer_for(number)
    return FIZZBUZZ if number.divisible_by_3? and number.divisible_by_5?
    return FIZZ if number.divisible_by_3?
    return BUZZ if number.divisible_by_5?
    number
  end
end