[eb4890]

I've had a go. It is hard because they don't define what a letter is (a-z, alphanumeric, non-whitespace). I tried with A-Za-z and got the correct answers for the test, but the incorrect answer for the website. Due to the way that the problem works that isn't too unlikely as all the letter function has to do is give the same answers on things like even-ness and whether it has a common factor with another number, things that aren't unlikely given the small amount of test data given.

[justin_vanw]

You can email me your solution at [e-mail] and I'll take a look. We just started doing the challenge with that site and there are probably kinks in the grading.

[eb4890]

I've noticed what I was doing wrong. I'm onto more interesting bits of the challenge, I hope. Thanks for the offer, though.