https://www.codewars.com/kata/beginner-series-number-3-sum-of-numbers/train/javascript
https://www.codewars.com/kata/find-the-odd-int/train/javascript
https://www.codewars.com/kata/sum-of-digits-slash-digital-root/train/javascript
https://www.codewars.com/kata/dubstep/train/javascript
https://www.codewars.com/kata/moving-zeros-to-the-end/train/javascript
https://www.codewars.com/kata/calculating-with-functions/train/javascript
https://www.codewars.com/kata/reverse-polish-notation-calculator/train/javascript