Python Program to find Factorial of a Large Number

October 14, 2022

Factorial of a Large Number

On this page we will learn how to find the Factorial of a Large Number in python.

Factorial of a number is product of all the positive numbers less then and equals to the number we are finding factorial. On this page we will see two different ways to solve the Question one by inbuilt function and another by creating a function.

  • Input : 5
  • Output : 120
  • Explanation : 5! = 5 x 4 x 3 x 2 x 1 = 120
Factorial of a Large Number in Python

Method 1 : Without Inbuilt Function

Algorithm

  • Start
  • Pass the value of n to a function
  • Initialize a variable name answer with value one
  • Run a while loop until value of n is greater then 1
  • Multiply the value of n with ans and assign the result in ans
  • Decrement value of n by one
  • Return the value of answer
Python Program to Find Factorial of a Large Number

Python code

Run 
def factorial(n):
    ans = 1
    while n > 1:
        ans *= n
        n -= 1

    return ans
n = 5
print(factorial(n))

Output

120

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Method 2 : Using Inbuilt Function for Factorial

Algorithm

  • From math library import Factorial Function
  • Assign to value to n for which you want to find Factorial
  • Pass the value of n to factorial function and assign the result to ans
  • Print ans

Python code

Run 
from math import factorial

n = 5

ans = factorial(n)

print(ans)

Output

120

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