Factorial Function in Python can be used to calculate a reusable method of factorial of a number. This function is used to return the value of factorial with loops or recursion function which eliminates the need to write programs again and again.
In this article, let us learn about factorial function in Python which can be used to solve factorial of a number n. We can also use a predefined function to calculate the factorial of a number.
What is Factorial Function In Python?
Factorial Function in Python can be used to calculate factorial using python programming language. Python provides a very simple and less lengthy format for running programs which calculates the factorial of a number. This function will accept an integer as an argument where we can either use loop or recursion to evaluate Factorial function.
You can start with a base condition where we will return 1 when the input number is either 0 or 1. For any other positive integer input you can multiply the value of n with factorial (n-1) and return the input value. The for loop multiplies each number by the result of the number and it iteratively goes through integer from 1 to n.
What is the logic of Finding Factorial?
The logic for factorial is to multiply a number by numbers below it which will come down to 1. Mathematically, it is represented by n! = n* (n-1)* (n-2)* (n-3)*……
You can use the formula n! = (n-1)! x n to calculate the factorial of the number n. You can use a loop, linked list or recursion method to calculate the factorial of a number. The symbol of factorial is given by “!” where a number “n” factorial of a number is represented by n!
Read more: Factorial Program In Java For Beginners
How to Use Python Math.factorial() Function?
You can use the Python programming language library to calculate the factorial of a number. This library can be used to calculate the factorial of a number and return the number. We can import the “math” module which allows you to compute the factorial of a number.
| import math
result = math.factorial(n) |
Where, n represents the factorial to be computed. We can return the factorial of number n!. We can only calculate non negative integers are allowed. Let us understand the usage of Math function in Python to calculate the factorial of a number.
| import math
num = int(input(“Enter a number: “)) if num < 0: print(“Factorial is not defined for negative numbers.”) Else: print(f”Factorial of {num} is {math.factorial(num)}”) |
Why Is Factorial Used So Much?
Factorial is the calculation of the number of different permutations you can have with given “n” items. For example 3 items can be arranged in 6 ways which are calculated using factorial, 3!. For example, let us suppose we have X, Y, and Z, we can arrange them in the following ways.
| XYZ
XZY YXZ YZX ZXY ZYX |
There are six possible combinations of these given 3 numbers in the factorial. You can calculate the factorial of 0 which can be arranged in exactly one way. Let us understand the practical implementation of Factorial with a real world example below.
Example of Factorial Function In Python
Example Problem: Arranging Books on a Shelf. Imagine you have 5 different books and you want to arrange them in a row on a shelf. How many different ways can you arrange these books?
Since each book must be placed in a unique order, we use factorial notation to determine the number of possible arrangements.
The total number of arrangements is given by 5! (5 factorial):
5!=5×4×3×2×1=1205!=5×4×3×2×1=120
So, there are 120 different ways to arrange these 5 books on a shelf! Just like the word “camper,” factorial helps us calculate the number of unique sequences when arranging distinct objects.
Algorithm for Factorial In Python Using Loops
Let us understand how we can use loops to solve factorial problems using a programming language i,e. Python.
- Initialize the factorial function variable.
- We have to use a loop which can either be for loop or while loop.
- Return the value with the complete outcome.
Python Code to Find Factorial using For Loops
| def factorial(n):
if n < 0: return “Factorial is not defined for negative numbers.” fact = 1 for i in range(1, n + 1): fact *= i # Multiply each number from 1 to n return fact print(f”The factorial of {num} is {factorial(num)}”) |
Python Code to Find Factorial using While Loop
| def factorial_while(n):
if n < 0: return “Factorial is not defined for negative numbers.” fact = 1 i = 1 while i <= n: fact *= i i += 1 return fact print(f”The factorial of {num} is {factorial_while(num)}”) |
Why Using Function Approaches Good In Python?
Functions are a very useful and productive approach in solving factorial using Python programs.
- Using a Function approach in Python allows you to use reusable code multiple times without having to write the code repeatedly.
- When you break down a program into function it helps to make it easier to read and maintain.
- You can easily test and fix individual functions rather than searching for errors in a long script code.
- It allows modular programming which means functions can be used for executing specific functions such as factorial function in Python calculates factorial of a number.
- It helps in implementing recursion and is useful in problems like fibonacci, factorial, and tree traversal.
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Factorial Function In Python FAQs
Q1. What are factorial functions in Python?
Ans: Factorial is the calculation of the number of different permutations you can have with given “n” items. For example 3 items can be arranged in 6 ways which are calculated using factorial, 3!.
Q2. Why is the Factorial function in Python useful?
Ans: Factorial function in Python is useful because it makes your code reusable, readable, easy debugging, and recursion.
Q3. Can we use loops to calculate factorial?
Ans: Factorials of a number can be calculated using loops i,e. For loops and while loops.
Q4. Is recursion possible in factorial function in Python?
Ans: Recursion can be used to solve factorial in Python which involves having a base condition which returns 1 when the number becomes equal to 0 or 1 and in other conditions it keeps on multiplying the number with one less number.
