My favorite is Chisenbop[0], the Korean finger-counting system, that lets you count/add/subtract easily to 100. It isn't as intuitive, but it is quite fun. [0]

My favorite is Chisenbop[0], the Korean finger-counting system, that lets you count/add/subtract easily to 100. It isn't as intuitive, but it is quite fun. [0]: https://en.wikipedia.org/wiki/Chisanbop https://en.wikipedia.org/wiki/Chisanbop