module CalculatorModule
  class Numeric
    def add(num)
      self + num
    end
  end
  class Numeric
    def subtract(num)
      self - num
    end
  end
  class Numeric
    def multiply_by(num)
      self * num
    end
  end
  class Numeric
    def divide_by(num)
      self / Float(num)
    end
  end

class TestClass
    include CalculatorModule
end
end