# Effective Ways To Find Functions Of Factorial In Python

In the modern world of technology, Artificial Intelligence, coding, Data science are on another level. No matter how vast or how far they have reached in the technological era, without the base, they are nothing. Python is the pillar for all the other programming languages. The functions of factorial in python help to deal with numbers in the programs.

Many of us have been taught to use factorials in our math class. In the python language, finding a factorial for a positive integer is also the same. You have to repeat the process of multiplying positive integers less than that number, that is, till the one.

In this blog, we will see how to find out the functions of factorial in Python. Here, we will use different functions like FOR Loop, WHILE Loop, and recursion. There are also some examples that will make you understand the functions of factorial in Python.

Table of Contents

**What is factorial and its formula?**

Factorial is the non-negative or positive integer. It is the multiplication or product of the positive integers. This product is less than or equal to the number of which you need to find the factorial.

The factorial is denoted by the symbol of exclamation (!).

**Formula of Factorial**

In every function of factorial in python, “n” is used, representing the factorial of a number. The formula is as follows:

n! = n*(n-1)*(n-2)*……..3*2*1

What is the purpose of factorials?It has been seen that factorials are useful to count the different orders or how many different ways you combine or do the thing(s). Suppose you want to perform a task and you do not know how many ways you can do this. This is where you can use the concept of factorial. It will help you to perform the task in n number of ways. This is the main purpose of using factorials. |

**Examples: How to calculate the factorial of a number?**

**9! factorial**

Here we have the factorial 9! So, we will multiply 9 with all the positive integers. Make sure the positive integers are less than 9.

*=> 9! = 9*8*7*6*5*4*3*2*1 = 362880*

**6! Factorial**

Here we have the factorial 6! So, we will multiply 6 with all the positive integers. Make sure the positive integers are less than 6. i.e. 5,4,3,2,1.

*=> 6! = 6*5*4*3*2*1 = 720*

Note:0! factorialHere we have the factorial 0! It is the trickiest factorial and an exception with an outcome of 1. The reason why the outcome is 1 is that 0 is not a positive integer, and so it defines itself. => 0! = 1 |

**How to find out the function of factorial in Python?**

There is a built-in function of factorial that can use as:

*math.factorial(x)*

Here, the function will return the argent x factorial. If the non-integral or negative value is provided, then the ** ValueError **will be generated.

**Let’s take an example to understand it:**

**Output: **

(‘The factorial of 5 = ‘, 120)

**Now, let’s check different methods of finding functions of factorial in Python.**

**Using For and range method**.

To get the value of functions of factorial, the for loop and range method is used.

**Output:**

(‘factorial of 0 = ‘, 1)

(‘factorial of 2 = ‘, 2)

(‘factorial of 5 = ‘, 120)

**Using recursion**

This method works well with the function to find the factorial of the desired number.

Let’s understand the working of recursion for a factorial ().

Input: Enter the number to find factorial 0

**Output: **

The factorial of zero is 1

**Using the While Loop**

This method is somewhat similar to the for loop method in finding a factorial in Python.

**Output:**

(‘factorial of 0 = ‘, 1)

(‘factorial of 2 = ‘, 2)

**Final Thoughts**

This blog will surely help you to understand the function of factorial in Python as it includes some of the essential functions that will make it possible to factorize.

In this blog, there are a total of four functions. Those are For Loop, Recursion, While Loop. The Python language has got great tools in its library. The tools are powerful enough to build in for a new program. That’s the reason why it is used extensively.

**Frequently Asked Questions**

**How do you write a factorial function?**

The functions of factorial can write as a recursive function. This will be as factorial(n) = n * (n-1) * (n-2) * …. * 1. It is also written as factorial(n) = n * factorial(n-1) recursively.

**Is factorial a function?**

The factorial is the math formula that represents the “!” symbol. The factorial formula multiplies the integers. These integers lie between the number and the number 1.