Factorial of a number: Learn what a factorial is

Learn what a factorial is, how to calculate it with examples, and how to write a factorial function in JavaScript. A factorial is the multiplication of all numbers between 1 and a number, and it is used to count the number of possible arrangements. We define factorial (n) such that if n = 0 or n = 1, it returns 1 (base case); otherwise, it returns n × factorial (n - 1). Thus, the problem is broken down into smaller subproblems until reaching the base case. The factorial of a positive number n is given by: factorial of n (n!) = 1 " 2 " 3 " 4....n The factorial of a negative number doesn't exist. And, the factorial of 0 is 1. The factorial of a number is the product of all positive integers less than or equal to that number. For example, the factorial of 5 (denoted as 5!) is 5 × 4 × 3 × 2 × 1 = 120. In Python, we can calculate the factorial of a number using various methods, such as loops, recursion, built-in functions, and other approaches.