Functions and recursion - Learn Python 3

2/16. What is a function?

Functions are the code sections which are isolated from the rest of the program and executed only when called. You've already met such functions as sqrt(), len() and print(). They all have something in common: they take parameters (zero, one, or several of them), and they can return a value (or they can return nothing, None). For example, the function sqrt() accepts one parameter and returns a value (the square root of the given number). The print() function can take various number of arguments and returns nothing.

Now we want to show you how to write a function called factorial() which takes a single parameter — the number, and returns a value — the factorial of that number.

Instructions

Click "Run" to see what happens in output!

def factorial(n):
    res = 1
    for i in range(1, n + 1):
        res *= i
    return res

Lesson 8. Functions and recursion

2/16. What is a function?

Instructions