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Factorial of a number in python

A non-negative integer’s factorial is the multiplication of all integers less than or equal to n.

n = int(input("Enter a number: "))    
fact = 1    
if n < 0:    
   print(" Factorial does not exist for negative numbers")    
elif n == 0:    
   print("The factorial of 0 is 1")    
else:    
   for i in range(1,n + 1):    
       fact = fact*i    
   print("The factorial of",n ,"is",fact)

Output:

Enter a number: 9

The factorial of 9 is 362880

Using Recursion

def factorial(num):  
    return 1 if (num==1 or num==0) else num * factorial(num - 1);  
  
n = int(input("Enter a number: "))
print("Factorial of",n,"is", factorial(n))

Output:

Enter a number: 7

Factorial of 7 is 5040

Using built-in function

Math module includes the build-in factorial() method.

import math  
def factorial(num):  
    return(math.factorial(num))  
n = int(input("Enter the number:"))  
fact = factorial(n)  
print("Factorial of", n, "is", fact)

Output:

Enter the number: 6

Factorial of 6 is 720

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