How to find Factorial of a Number using Python
Tags: python, webdev, beginners, programming
Published: 2023-07-13 05:23:53

## Introduction:

We will explore how to find the factorial of a number using Python with a step-by-step guide along with a code example to help you understand and implement factorial calculations efficiently. 
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## Understanding Factorial in Mathematical way

Factorial of a non-negative integer n, denoted as n!, is the product of all positive integers less than or equal to n. For instance, the factorial of 5 (5!) is calculated as 5 * 4 * 3 * 2 * 1, resulting in 120.


## Step 1: Recursive Approach

One way to calculate the factorial of a number is by using recursion. Recursive functions are functions that call themselves, simplifying the problem into smaller subproblems until a base case is reached. Let's define a recursive function to find the factorial of a number:

```
def factorial_recursive(n):
    if n == 0 or n == 1:
        return 1
    else:
        return n * factorial_recursive(n - 1)

```

In the code snippet above, we define a function `factorial_recursive` that takes an argument `n`. If `n` is equal to 0 or 1 (the base case), we return 1. Otherwise, we multiply `n` with the factorial of `n - 1` by recursively calling the `factorial_recursive ` function.

## Step 2: Iterative Approach

Another way to calculate the factorial of a number is by using an iterative approach. Iterative solutions involve using loops to iterate over a range of values and update the result incrementally. Let's define an iterative function to find the factorial of a number:

```
def factorial_iterative(n):
    result = 1
    for i in range(1, n + 1):
        result *= i
    return result

```

In the code snippet above, we initialize a variable `result` to 1. Then, using a `for` loop, we iterate from 1 to `n + 1` and multiply each value with the `result` variable, updating it at each iteration. Finally, we return the `result` as the factorial of the given number `n`.

## Step 3: Testing the Functions

```
number = 5

print(f"The factorial of {number} using recursive approach is: {factorial_recursive(number)}")

print(f"The factorial of {number} using iterative approach is: {factorial_iterative(number)}")

```

In the code snippet above, we define a variable `number` and set it to 5. Then, we use the `print` function to display the factorial of `number` using both the recursive and iterative approaches.

## Conclusion:

We explored two methods: recursive and iterative. The recursive approach simplifies the problem by breaking it down into smaller subproblems, while the iterative approach uses loops to incrementally calculate the factorial. Both methods are effective, and the choice depends on the specific requirements of your program. By understanding these approaches and using the provided code examples, you can now compute the factorial of any number efficiently in Python. Do more hands-on applications/programs using Python Programming. 

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