The for loop is also used for determining factorial in Python. In the case of factorial of 0 or a negative number, it will return 1 3. #Note: This program will work also for negative and zero. #factorial program using while loop n= int(input( 'Enter a number : ')) fact = 1 a=1 while a <= n : fact*=a a+=1 print('The factorial of ', n, ' is ', fact) In this, we will use the while condition to check whether a variable is less than equal to the given number, in order to ensure the number of iterations for getting the result.

This is the basic method of writing factorial code using iteration. Input =10 #Output Enter a number: 10 The factorial of 10 is : 3628800 2. # Factorial program using math module import math n = input('Enter a number: ') print('The factorial of ', n, ' is : ') print(math.factorial(int(n))) In this method, We have to import the math module and use the inbuilt factorial function in Python. Factorial Program in Python Using the math Module There are many ways to write a Python program for the factorial of a number.

If the previous condition is False then, return factorial.ĭifferent Ways of Writing a Factorial Program in Python.

Check whether the new value of n is greater than 1 if True then repeat step 5.

Now check multiply factorial with n i.e., (factorial×n) and decrement n by 1 i.e., (n-1).

If the number is equal to zero then return 1, otherwise move to the next step.

Check whether the number is greater than or equal to zero.

So Let’s understand the algorithm of factorial code. Before, writing python code for the factorial program, we must know the algorithm of this program.

Factorial function in python