As a 5-kyu teenage coder, this kata took me 1.5h to finish, and I learned a lot. Super hard and long!!! Probably 4 or 3 kyu kata. Appreciate the author!

wow.. some amazing solutions here.. :P

This is a suggestion and, as soon as it has not been incorporated in the kata, a spoiler, so please use the appropriate flag when doing that kind of things.

A few suggestions:
*This is first in a series, not serie.
*It would be nice to explain what a DNI is at the beginning.
*In your description you say a'This relation is that the

rest of the division of the large number by 23 is ..." in English, we usually say the remainder when dividing by 23 correlates to the letter in the following table"

*I'd suggest modifying your basic function def from def dni_solver(dni): return dni to def dni_solver(str); return dni because you are not feeding the function dni and expecting to return dni also
*In the description you say that the task is to determine the letter of the DNI number; so why not just provide a number and return a letter only? or is the task to provide the completed DNI
*Those comments aside, I did enjoy doing kata where one learns a bit about another culture.

Issue below was resolved by mistake.

I am not saying anything about quality and implementation, I'm just pointing out that this has been done before.

hahahaha, greate!!!

Well you're right it was a terrible kata and also my first one. This was the first of a possibly greate serie that could ends with an incredible one, but I think I should restructure it better.
We learn from mistakes.

It's not mine either ... double benefits !
Not only will Codewars improve your programming skills, but also your english skills ;)

I'm starting to create katas, I don't think it's that bad, but for that reason you can vote.

Thank you very much. Positive feed back It's great. And I'm glad you like the serie.
It's my first one and I was testing.

it's obvious that english is not my native language ;)

Thanks for the help

Thanks :)