✅ Factorial of a Number (Classic Example)
def factorial(n):
    # Base condition: factorial of 0 or 1 is 1
    if n == 0 or n == 1:
        return 1
    # Recursive call
    return n * factorial(n - 1)

print(factorial(5))  # Output: 120
✅ Fibonacci Sequence
def fibonacci(n):
    # Base cases
    if n == 0:
        return 0
    elif n == 1:
        return 1
    # Recursive calls
    return fibonacci(n - 1) + fibonacci(n - 2)

print(fibonacci(6))  # Output: 8
✅ Sum of Natural Numbers
def sum_natural(n):
    # Base case
    if n == 0:
        return 0
    # Recursive case
    return n + sum_natural(n - 1)

print(sum_natural(5))  # Output: 15
✅ Reverse a String
def reverse_string(s):
    # Base case: if string is empty or one character
    if len(s) <= 1:
        return s
    # Recursive case: reverse the rest and append first character
    return reverse_string(s[1:]) + s[0]

print(reverse_string("hello"))  # Output: "olleh"