I can across an exotic number system known as a sandpile on Numberphile video.

Exploiting Julia fantastic type system and very cool index handling, I put implements that sandpile addition operator demonstrated in the Numberphile video.

The notebook can be found here.

I was recently introduced to Kaperkar’s Constant.
It is quite magical. You take any four digit number , sort the digits from highest to lowest to create a new number , sort the digits from lowest to highest to get , and calculate and new number . You repeat this procedure enough times and you end up with .

I made a nifty implementation of that in Julia below.