Using Python, we can calculate factorials using recursion. Defining a recursive function to find the factorial of a nonnegative integer in Python can be done in the following code.

```
def factorial_with_recursion(n):
if isinstance(n,int) and n >= 0:
if n == 0 or n == 1:
return 1
else:
return n * factorial_with_recursion(n-1)
else:
return "Not valid input"
```

When working with numbers, one common calculation which is easy to perform in Python is finding the factorial of a number.

We can find the factorial of a number in Python in a number of ways.

One such way is to use recursion to calculate the factorial of a number.

To use recursion, we need to define a base case for our recursive function, and define the recursive step where we will call the recursive function again.

## Using Recursion to Calculate Factorial of Number in Python

Finding the factorial of a number using recursion is easy. To calculate the factorial of a number in Python using recursion, we need to define the base case, and then define the recursive step.

The base case for the factorial function is when n is 0 or 1. In that case, we want to return 1. If n is greater than 1, then we will call the function again with n – 1 as the input.

Below is a recursive function for calculating the factorial of a number. I’ve also included some input validation to make sure that the input is a nonnegative integer.

```
def factorial_with_recursion(n):
if isinstance(n,int) and n >= 0:
if n == 0 or n == 1:
return 1
else:
return n * factorial_with_recursion(n-1)
else:
return "Not valid input"
print(factorial_with_recursion(3))
print(factorial_with_recursion(5))
print(factorial_with_recursion(8))
print(factorial_with_recursion(12))
#Output:
6
120
40320
479001600
```

As you can see above, calculating the factorial of a number in Python using a recursive function is pretty straightforward.

Hopefully this article has been useful for you to learn how to use Python to calculate the factorial of a number using recursion.