# Exercise: Factorial of a Number

This lesson will give an exercise to test the learners on basic Python skills.

## We'll cover the following

## Problem Statement

In this challenge, you must implement the `factorial()`

function. It takes an integer as a parameter and calculates its factorial.

The factorial of a number,

n, is its product with all the positive integers smaller than n.

$factorial(n) = n*(n-1)*(n-2) *..... * 1$

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