This solution is no longer valid.

its asked to order by name asc

No, that would lead to infinite recursion.

good!

I like the usage of recursion, pretty cool solution!

technical note:
"have been rounded" is not past tense.
And actually we can use
Present perfect for future... as written in
https://learnenglish.britishcouncil.org/grammar/english-grammar-reference/present-perfect

What is the point of using a recursion when you can do it much faster and simpler with a loop? I think recursion should be used only when it's necessary - going through all tree branches, for example.

Thank you so much!

Thanks a lot!)

'Looks like you've solved it'

Thank you.

Wow, nice use of strtr. Thanks for sending me to the PHP docs. Any advantage over passing arrays to str_replace?

I agree that this problem should be at least 6 kyu.
But it's not true that you need knowledge of an obscure mathematical construct. You can "just" (not that easy) follow the instructions and get the answer (look at my solution for example).
Edit: I've played with the obscure solutions so if you click on "View solution" it might not show what I was talking about.