721 B
721 B
importance: 4
Calculate factorial
The factorial of a natural number is a number multiplied by "number minus one", then by "number minus two", and so on till 1. The factorial of n is denoted as n!
We can write a definition of factorial like this:
n! = n * (n - 1) * (n - 2) * ...*1
Values of factorials for different n:
1! = 1
2! = 2 * 1 = 2
3! = 3 * 2 * 1 = 6
4! = 4 * 3 * 2 * 1 = 24
5! = 5 * 4 * 3 * 2 * 1 = 120
The task is to write a function factorial(n) that calculates n! using recursive calls.
alert( factorial(5) ); // 120
P.S. Hint: n! can be written as n * (n-1)! For instance: 3! = 3*2! = 3*2*1! = 6