Executing Gummiworms The trials and tribulations of a grumpy curmudgeonly old git

A hint for question 10

I've had a few emails and a couple of pings via IM that Question 10 is really hard It is supposed to be but maybe it is a little too hard after all. It is possible to work it out but you probably do have to know something about a certain branch of mathematics and probably just happen to know the answer.

So here is a clue to help you on your way. ROT13'ed so that people who don't want a hint can ignore it.

--rot13--

Gur frdhrapr vf eryngrq gb n cebcregl bs n pynff bs vagrtref engure guna gur vagrtref gurzfryirf orvat vzcbegnag.

--end-of-rot13--

Hopefully this hasn't made it too easy.