In [2]:

    

a = 1*2*3*4*5*6*7*8*9*10*11*12*13*14*15*16*17*18*19*20
a = a*21*22*23*24*25*26*27*28*29*30*31*32*33*34*35*36*37*38*39*40
a = a/ (1*2*3*4*5*6*7*8*9*10*11*12*13*14*15*16*17*18*19*20)
a = a/ (1*2*3*4*5*6*7*8*9*10*11*12*13*14*15*16*17*18*19*20)
print a


    

    




137846528820

In [3]:

    

s =1
for i in range(1, 41):
    s = s*i


    

In [5]:

    

for i in range(1, 21):
    s = s/i
    s = s/i


    

In [6]:

    

s


    

    
Out[6]:





137846528820L

In [7]:

    

from math import factorial


    

In [8]:

    

import math


    

In [10]:

    

factorial(40)/factorial(20)/factorial(20)


    

    
Out[10]:





137846528820L