Python Coding challenge - Day 474| What is the output of the following Python Code?

 

Code Explanation:

1. Function Definition

def f(n):

This defines a function f that takes one argument n.

It is intended to compute the factorial of n recursively.

2. Base Case for Recursion

    if n == 0: return 1

If n is 0, the function returns 1.

This is the base case of the recursion.

0! = 1 by mathematical definition.

3. Recursive Case

    return n * f(n - 1)

If n > 0, the function returns n * f(n - 1).

This is the recursive step: it multiplies n by the factorial of n-1.

For example, f(3) returns 3 * f(2), which returns 3 * 2 * f(1) → and so on until f(0).

4. Function Call and Result Conversion

print(len(str(f(20))))

This calls the function with n = 20, so f(20) computes 20! (20 factorial).

20! = 2432902008176640000

Then str(...) converts the result to a string: "2432902008176640000"

len(...) gets the number of characters (digits) in the string.

Final Output

The number of digits in 20! is 19.

>>> print(len(str(f(20))))

19