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1. Print 1 to N Recursively2. Factorial Using Recursion3. Print N to 1 Recursively4. Even Numbers 1-N Recursively5. Odd Numbers 1-N Recursively6. Sum of First N Natural Numbers Recursively7. Power x^n Recursively8. Nth Fibonacci Recursively9. Fibonacci Series Recursively10. Sum of Digits Recursively

Factorial Using Recursion

Calculate factorial recursively.

IntermediatePhase 3 - Level 1: Basic RecursionExample 2 of 10
factorial-using-recursion.py
1def factorial(n):
2    # Base case
3    if n == 0 or n == 1:
4        return 1
5    
6    # Recursive case
7    return n * factorial(n - 1)
8

9# Test
10n = int(input("Enter n: "))
11result = factorial(n)
12print(f"Factorial of {n} is {result}")

Output

Enter n: 5
Factorial of 5 is 120

What's going on

Factorial(n) = n * Factorial(n-1).

Key Concepts:

Base case: factorial(0) = factorial(1) = 1
Recursive case: n * factorial(n-1)
Function calls itself with n-1

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