题解 | #球的表面积#

import math
class Circle:
    def __init__(self,r):
        self.r = r
    def getsize(self):
        return '{:.2f}'.format(4*self.r*self.r*math.pi)
lst = [1, 2, 4, 9, 10, 13]
for i in lst:
    circle = Circle(i)
    print(circle.getsize())