Just ditch the Linq, at least in this case. Slow as molasses. My code is readable, maintainable, and executes 2.5 to 3 times faster. Linq is too often a crutch for lazy coding.

@gaelanmcmillan: "People love a compact Linq solution" to the detriment of all. Most of those compact solutions are significantly slower to execute. Simple loops, while more verbose, will usually be better in execution speed, and much, much easier to read and maintain.

That code takes 2.5 to 3 times as long to execute compared with mine. That is significant.

From the description, it is not expected to. but yeah it doesn't.

What do you mean, DoimanII ?

using ToString() is a bad idea, because the ToString() can be overriden and it can return a different result.

Woooow! Who do you do this>?!

The correct answer.

Lol no it doesn't

Even if it solves this kata and is upvoted as hell, is does not work with two digit numbers ;)