# Defining the calculate method, takes 3 parameters, first, second and operator
def calculate(first, second, operator)
  # Testing the content of Operator
   case operator
    # If the content is + we add the 2 numbers and return the result
    when "+" then (return "#{first} #{operator} #{second} result in #{first + second.to_f}")
    # If the content is - we substract the 2 numbers and return the result
    when "-" then (return first - second.to_f)
    # If the content is * we multiply the 2 numbers and return the result
    when "*" then (return first * second.to_f)
    # If the content is / we divide the 2 numbers and return the result
    when "/" then (return first / second.to_f)
    # If not an valid operation, return an error message
    else (return "wrong operation M8!")
  end # End of case
end # End of method