i like this solution, because it makes use of ruby methods that i rarely if ever use, upto and keep_if. ;)

hehehe. noice.

or u can save the calculations

Fixed

Wanting to have more tags is really no issue!

Because sometimes we want to convert from one type to another.

I benchmarked it and found it to be at least twice as slow as the ternary implemenatation. It looks nice though.

It's a question of what's more idiomatic. See Avdi Grimm's master work: Confident Ruby

what does the ampersand do?
O(n)

relevant: https://xkcd.com/1445/

Hello

This is the second time i've seen the single & used in a function,

Can you provide some insight into this?

Exactly the one I thought about initially, but this way you would do to square roots, one for nothing :(

Agreed :) Just a habit, I guess.

I think this kind of misses the point of the kata. It feels like your 'clever' solution was really just a cheat. For some of the Katas the point is to figure out 'clever' solutions (aka cheat) but not this one. Or maybe its just a game.