Fixed

Wanting to have more tags is really no issue!

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/

Agreed :) Just a habit, I guess.

The truth is many things are simple, and knowing that is itself valuable.

But I can agree with pointing a couple steps away from the exact method, to build the habit/skill of searching for the simple answers.

For some reason, I can't add more tags. May be I'm doing something wrong, but the tags I set in the description don't show up eventually for the kata.

See the comments below. I think that we need to use integers for the Ruby version. The description is a bit confusing. Still in the process of figuring that out.

Golfing here, not writing a production calculator in 3-4 lines of code... far from best practice, if you actually used this I would laugh at you...