>>> while True:
    k = float(input('K ? '))
    print("%g Kelvin = %g Celsius = %g Fahrenheit = %g Rankine degrees."
          % (k, k - 273.15, k * 1.8 - 459.67, k * 1.8))


K ? 21.0
21 Kelvin = -252.15 Celsius = -421.87 Fahrenheit = 37.8 Rankine degrees.
K ? 222.2
222.2 Kelvin = -50.95 Celsius = -59.71 Fahrenheit = 399.96 Rankine degrees.
K ?