Glad my solution took me hours to write, and is 35 lines. (-_-) To be fair to myself, I was hellbent on preserving the data type and not converting the input to a string. Why? Not sure exactly. But I did it.

Clever. I knew you could generate an array of numbers but never needed it so didn't know how until this kata. I like this solution.
I am a big fan of Linq as well so I like Linq solutions.