class Even
  def even(n)
    n.even?
  end
end

A bit tounge in check, but I love Ruby too for things like this.

It was defensive, I'm guessing you feel personally attacked as your update has allowed this loophole. Sorry it wasn't personal but the idea of getting annoyed at a user because you left a loophole seems naive to me...

I haven't been coding long but I've enjoyed solving these little problems on CW and I've learnt a lot thanks to it but if this is enough to get banned I don't really care.

Hopefully somebody comes along with better update that closes this and I'll have another go in the future. It looks like another commenter may have done just that but I'm not skilled enough to say whether everything is fine.

Anyway thanks for making my first attempt at feedback such an unpleasant experience, with any luck the next time will be better or I just won't bother. Maybe you should have a think about what actually makes CW a worse place?

Could you check this fork?

Oh, that wasn't defensive, that was full-on offensive. I was calling you a cheat.

This kata was authored when restricting Math.random was possible. Maybe it should be retired, instead of updated to the current version, after all. And maybe you should just be banned.

ETA: I did not much expect, but at least hope, that people would actually read the description, and follow instructions. Why would you insist on making CW a worse place for everybody, where restrictions have to be enforced? Why do you feel the need, the need to cheat?

if the tests pass then I don't see how you can expect this to not happen.

I thought the feedback might be useful, no need to get defensive.

Could anyone recommend some topics to study to understand this?

I loved it.