Python program to find factorial of a number using while loop

In this tutorial, we will discuss Python program to find factorial of a number using the while loop

In this post, we use if statements and while loop to calculating factorial of a number and display it

Factorial is a product of all positive descending integer begins with a specified number (n) and calculates up to one

Factorial of n is

Example

factorial of 5 is

5!=5*4*3*2*1=120

factorial of 7 is

7!=7*6*5*4*3*2*1=5040

The factorial of a positive number n is given below

factorial of n is

n!=n*(n-1)*....2*1

The user can provide numbers as they wish and get the factorial according to their input

Here, we can follow some procedure to reach the completion of this program

Take a number of input from the user
Initialize a factorial variable to 1
A while loop is used to multiply the number to find factorial (for the continuing process)
This process continue until the value of the number is greater than zero
The factorial of the given number is printed

Program 1

#Python program find factorial of a number
#using while loop

num=int(input("Enter a number to find factorial: "))
#takes input from user

factorial=1;  #declare and initialize factorial variable to one

#check if the number is negetive ,positive or zero
if num<0:
   print("Factorial does not defined for negative integer");
elif(num==0):
    print("The factorial of 0 is 1");
else:

  while(num>0):
        factorial=factorial*num
        
        num=num-1
        
  print("factorial of the given number is: ")
  print(factorial)

Case 1

Enter a number to find factorial: -2
Factorial does not defined for negative integer

Case 2

Enter a number to find factorial: 0
The factorial of 0 is 1

Case 3

Enter a number to find factorial: 5
factorial of the given number is: 
120

In the above program, we can check the given number negative, zero or positive using if elif else statements in python

if the number is negative, the output is displayed as follows “factorial does not available for a negative number”

if the number is zero, the output is displayed as follows “The factorial of 0 is 1”

otherwise, if the number is positive, the while loop calculates factorial of the given number

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Python program to find factorial of a number using while loop