Temperature converter that seems to violate SRP
class Numeric

  def fahrenheit_to_celsius
    (self - 32) * 5 / 9
  end

  def celsius_to_fahrenheit
    self * 9 / 5 + 32
  end

end

p -7.5.celsius_to_fahrenheit #=&gt; 18.5


Classes are open for a reason in ruby. A temperature is just a number, converting it is just a method. The accuracy thing disappears by itself - an integer results in an integer, a float will give a float.