freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-algorithm-scripting/factorialize-a-number.english.md

id, title, isRequired, challengeType

id	title	isRequired	challengeType
a302f7aae1aa3152a5b413bc	Factorialize a Number	true	5

Description

Return the factorial of the provided integer. If the integer is represented with the letter n, a factorial is the product of all positive integers less than or equal to n. Factorials are often represented with the shorthand notation n! For example: 5! = 1 * 2 * 3 * 4 * 5 = 120 Only integers greater than or equal to zero will be supplied to the function. Remember to use Read-Search-Ask if you get stuck. Write your own code.

Instructions

Tests

tests:
  - text: <code>factorialize(5)</code> should return a number.
    testString: assert(typeof factorialize(5) === 'number', '<code>factorialize(5)</code> should return a number.');
  - text: <code>factorialize(5)</code> should return 120.
    testString: assert(factorialize(5) === 120, '<code>factorialize(5)</code> should return 120.');
  - text: <code>factorialize(10)</code> should return 3628800.
    testString: assert(factorialize(10) === 3628800, '<code>factorialize(10)</code> should return 3628800.');
  - text: <code>factorialize(20)</code> should return 2432902008176640000.
    testString: assert(factorialize(20) === 2432902008176640000, '<code>factorialize(20)</code> should return 2432902008176640000.');
  - text: <code>factorialize(0)</code> should return 1.
    testString: assert(factorialize(0) === 1, '<code>factorialize(0)</code> should return 1.');

Challenge Seed

function factorialize(num) {
  return num;
}

factorialize(5);

Solution

function factorialize(num) {
  return num < 1 ? 1 : num * factorialize(num - 1);
}

factorialize(5);