Hello Programmers, In this blog post you will learn to find the Factorial of a number in Python. Factorial is the multiplication of all the numbers before the number till 1 and the number itself. It’s very easy to find the factorial of a number in Python. Let us learn about it in detail:-
Factorial of Numbers
0! = 1
1! = 1
2! = 2 * 1 = 2
3! = 3 * 2 * 1 = 6
4! = 4 * 3 * 2 * 1 = 24
n! = n * (n-1) * (n-2) ………….. * 2 * 1
Way to find Factorial of a number in python:-
In this code, we have taken n as input from the user to get the value of the number whose factorial users want to find. Then we will declare the value of fact as 1 because we will use it afterward. Now we will use a loop because a user can enter any number wheater its positive, Negative, or Zero.
So in the first case of the loop when a user enters a negative number or number < 0 then the output will be Factorial if this number cannot be found. In the second case where the number is equal to 0, we will give its value 1 because the factorial of 0 is 1.
Now in the third and last case where the number is greater than 1, we will start a loop from the range 1 to n+1 numbers and will apply the formula factorial = factorial * I Which is used to find the factorial of a number. Now we can print and you will get a factorial of that particular number.
Factorial.py
OUTPUT
Case 1:-
Enter a Value to find Factorial: 0
Factorial of 0 is 1
Case 2:-
Enter a Value to find Factorial: -1
Factorial of this Number Cannot be found
Case 3:-
Enter a Value to find Factorial: 5
The factorial of 5 is: 120
Case 4:-
Enter a Value to find Factorial: a
Traceback (most recent call last):
File “d:\factorial.py”, line 1, in <module>
n = int (input ( “Enter a Value to find Factorial: ” ))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: invalid literal for int() with base 10: ‘a’
It will show an error in this case beacuse we have given a as input. So it will not accept it as a is a alphabet and we have already declared that in n only integer can be written because we want only numbers to operate this code.
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