Python Program to Find Factorial of Number Using Loop

Here you will get python program to find factorial of number using for and while loop.

Factorial of a number is calculated by multiplying it with all the numbers below it starting from 1.

For example factorial of 4 is 24 (1 x 2 x 3 x 4).

Below program takes a number from user as an input and find its factorial.

Python Program to Find Factorial of Number

Using For Loop


enter a number: 5
factorial of 5 is 120

Using While Loop


enter a number: 4
factorial of 4 is 24

Video Tutorial

Comment below if you have any queries related to above python factorial program.

21 thoughts on “Python Program to Find Factorial of Number Using Loop”

    1. Because range(start, end) function will generate numbers from start and end-1. In above program we want to generate numbers from 1 to num, I have used num+1 that means (num+1)-1 which ultimately means num.

    2. As we know that if we write only num,it will take range (1,num-1)means if we write only num it will range from 1 to num -1. And if we range (1,num+1)it range the number also that you have entered.


    3. Because if you give only num it will end with 1 less number
      Eg.for i in range(1,5)
      It will olny print 4 number there fore we add num+1

  1. def factorial(a):
    for i in range(1,a+1):
    result= result*i
    return result
    a = input(‘ur number please ‘)
    y = (factorial(a))
    print(y + str (‘is ur answer’))
    can any body tell me where is the problem

    1. Namit Vithalrao Shastri

      You first define function and then you didn’t use it . So off course no output. Example :- factorial(4)

    2. This is what I used and it worked on Codio:

      t = 1
      for i in range(1, N+1):
      t = t * i
      if N – i == 0:

  2. sven Brodowski

    i’m Sven Brodowski
    my english is not verry good

    youre programms are super
    I’m learning Python and Java

    my Questions
    have you got a programm in Python
    where can do inverse Matrix

    I live in heilbronn germanny

    ok see you later

  3. Hello!

    I have read my book from Codio and have attempted the challenge. Here is what I have coded:

    # Get N from the command line
    import sys
    N = int(sys.argv[1])

    # Your code goes here
    print (N)

    It is telling me my output is 4.
    I am confused, because if N is 4 based upon what the user input, why is it not completing the calculation?

    Can you help?

  4. An integer t, 1<=t<=100, denoting the number of testcases, followed by t lines, each containing a single integer n, 1<=n<=100.

    For each integer n given at input, display a line with the value of n!
    Find the factorial!!

    1. def factorial(a):
      if a == 0 or a ==1:
      return a
      return a * factorial(a-1)

      a = int(input())
      y = factorial(a)
      print( y)

  5. With the for loop, how would I be able to have it display the actual calculation along with the answer, for example if user enters 4, I need it to display:

    4! = 1 x 2 x 3 x 4 = 24

    I am able to get the code to display the answer, however not the actual equation.

    Thanks for your help in advance!

  6. num = int(input(“enter a number: “))

    fac = 1

    for i in range(1, num):
    fac = fac *num
    num = num-1
    print(“factorial of “, num, ” is “, fac)

  7. Giovanny Guthiery Soares de Oliveira

    def fat(n):
    a = n – 1
    while a != 1:
    n *= a
    a -= 1
    print(f’O fatorial de {c} é igual a {n}’)
    c = int(input(‘Digite Um Numero: ‘))

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