#0306

Factorial of a Number

EasyPython15 min10 XP

Problem

Given a non-negative integer n, return n!. By definition, 0! is 1.

Why This Matters

Factorial is a classic warm-up for loops, multiplication accumulation, base cases, and recursion thinking.

Function Signature

def factorial(n):

Examples

Example 1

Inputn = 5

Output120

5! means 5 * 4 * 3 * 2 * 1, which is 120.

Constraints

Return the exact requested value.
Handle edge cases cleanly.
Prefer clear Python code before clever one-liners.

CodePython

def factorial(n):
    """
    Input example: n = 5
    Return: 120
    Return the value from the function so the tests can compare it. Do not print unless the prompt asks.
    """
    # write your code here
    return 0

def factorial(n):
    """
    Input example: n = 5
    Return: 120
    Return the value from the function so the tests can compare it. Do not print unless the prompt asks.
    """
    # write your code here
    return 0

Visible browser tests run here when available.

Testcases2 visible / 3 hidden categories

Five factorial

Input5

Expected120

Multiply values from 2 through 5.

Zero factorial

Input0

Expected1

0! is defined as 1.

Hidden Test Categories

n = 1larger nnon-negative input only