Math
==

- Create a square root function.
- Given a string such as "123" or "67", write a function to output the number represented by the string without using casting.
- Make a program that can print out the text form of numbers from 1 - 1000 (ex. 20 is "twenty", 105 is "one hundred and five").
- Write a function that parses Roman numerals.
  - E.g. `XIV` returns `14`.
- Write in words for a given digit.
  - E.g. `123` returns `one hundred and twenty three`.
- Given a number `N`, find the largest number just smaller than `N` that can be formed using the same digits as `N`.
- Compute the square root of `N` without using any existing functions.
- Given numbers represented as binary strings, and return the string containing their sum.
  - E.g. `add('10010', '101')` returns `'10111'`.
- Take in an integer and return its english word-format.
  - E.g. 1 -> "one", -10,203 -> "negative ten thousand two hundred and three".
- Write a function that returns values randomly, according to their weight. Suppose we have 3 elements with their weights: A (1), B (1) and C (2). The function should return A with probability 25%, B with 25% and C with 50% based on the weights.
  - [Source](http://blog.gainlo.co/index.php/2016/11/11/uber-interview-question-weighted-random-numbers/)
- Given a number, how can you get the next greater number with the same set of digits?
  - [Source](http://blog.gainlo.co/index.php/2017/01/20/arrange-given-numbers-to-form-the-biggest-number-possible/)