from math import pi

def cal(r):
    s = 4*pi*r**2
    s = round(s, 2)
    return s

x = [1, 2, 4, 9, 10, 13]

for i in x:
    print(cal(r=i),end = "\n")

注意python里^符号不是幂运算，使用**或者pow(r,2)