Loading collection data...
Collections are a way for you to organize kata so that you can create your own training routines. Every collection you create is public and automatically sharable with other warriors. After you have added a few kata to a collection you and others can train on the kata contained within the collection.
Get started now by creating a new collection.
updated
Right, oups
"digital root" actually
This is called digital sum (i.e digit sum) in the simple case. so i would cal it a reapteded digital sum
Yup, came here to say that. all the invalid input tests are mostly just annoying, don't make much sense, and make everybody's code look worse.
This comment is hidden because it contains spoiler information about the solution
That kata allows use of strings and lists, this one doesn't (Woops, didn't notice this is from 3 years ago, it probably didn't require that back then)