For all practical uses x'=(x*8+1) mod 49 is a simple PRNG that can be executed mentally easily. If you seed it with the next best number you see it gives suitably random numbers for every-day purposes (and when no dice are available). Note that this is taken from TAoCP by Knuth. I use it for fair choices and mental story telling.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 116.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)