import math

def main ():
    beregn_volum(2.5)
    beregn_volum(5.0)
    beregn_volum(7.5)

def beregn_volum(radius):
    volum_kule = format (((4*math.pi*radius**3)/3) , ".2f")
    print ("Volumet til kula med radius " , radius , "er: " , volum_kule)

main()