I am a bit confused. How does [9,10,0] represent the number 999? I can see, I guess that the 10 can be converted to a 9(?) but why would it not be 990 then?

I think this Kata could be given a little bit more scope by having more responses so you could maybe be forced to think about storing replies in a dictionary or something? Just an idea :)

I enjoyed this Kata. Thank you for creating it!

I can't however rate the Kata as 'ready' even though I have completed it?