Solved Issue 1008

CONTRIBUTING.md

@@ -8,8 +8,7 @@
 
 **Contributing New Translation**
 
-- Create new `README.xx-XX.md` file with translation alongside with 
-main `README.md` file where `xx-XX` is [locale and country/region codes](http://www.lingoes.net/en/translator/langcode.htm).
+- Create new `README.xx-XX.md` file with translation alongside with main `README.md` file where `xx-XX` is [locale and country/region codes](http://www.lingoes.net/en/translator/langcode.htm).
 For example `en-US`, `zh-CN`, `zh-TW`, `ko-KR` etc.
 - You may also translate all other sub-folders by creating 
 related `README.xx-XX.md` files in each of them.

src/algorithms/math/factorial/README.en-IN.md

@@ -0,0 +1,35 @@
+# Factorial
+
+_Read this in other languages:_
+[_简体中文_](README.zh-CN.md), [_Français_](README.fr-FR.md), [_Türkçe_](README.tr-TR.md), [_ქართული_](README.ka-GE.md), [_Українська_](README.uk-UA.md).
+
+In mathematics, the factorial of a non-negative integer `n`,
+denoted by `n!`, is the product of all positive integers less
+than or equal to `n`. For example:
+
+```
+5! = 5 * 4 * 3 * 2 * 1 = 120
+```
+
+| n   |                n! |
+| --- | ----------------: |
+| 0   |                 1 |
+| 1   |                 1 |
+| 2   |                 2 |
+| 3   |                 6 |
+| 4   |                24 |
+| 5   |               120 |
+| 6   |               720 |
+| 7   |             5 040 |
+| 8   |            40 320 |
+| 9   |           362 880 |
+| 10  |         3 628 800 |
+| 11  |        39 916 800 |
+| 12  |       479 001 600 |
+| 13  |     6 227 020 800 |
+| 14  |    87 178 291 200 |
+| 15  | 1 307 674 368 000 |
+
+## References
+
+[Wikipedia](https://en.wikipedia.org/wiki/Factorial)

src/algorithms/math/factorial/factorialRecursive.js

@@ -1,7 +1,11 @@
 /**
  * @param {number} number
  * @return {number}
+ * @throws {Error} if number is negative
  */
 export default function factorialRecursive(number) {
+  if (number < 0) {
+    throw new Error('Factorial is not defined for negative numbers.');
+  }
   return number > 1 ? number * factorialRecursive(number - 1) : 1;
 }