James Clewett graphs one of his favourite books and explains the significance of 400. More links & stuff in full description below ↓↓↓ The extra video about the weird bit of graph is at http://youtu.be/wYo0SOMlxuc The book is The Warlock of Firetop Mountain, the first in the Fighting Fantasy series. The same principle applies to the likes of "Choose Your Own Adventure" books. James Clewett tweets (occasionally) at https://twitter.com/_Itch_ More videos featuring James: http://www.youtube.com/playlist?list=PLeaKaAcimVK3tyCR6ugbA4Yx7eaP0MIoX NUMBERPHILE Website: http://www.numberphile.com/ Numberphile on Facebook: http://www.facebook.com/numberphile Numberphile tweets: https://twitter.com/numberphile Subscribe: http://bit.ly/Numberphile_Sub Videos by Brady Haran Patreon: http://www.patreon.com/numberphile Brady's videos subreddit: http://www.reddit.com/r/BradyHaran/ Brady's latest videos across all channels: http://www.bradyharanblog.com/ Sign up for (occasional) emails: http://eepurl.com/YdjL9 Numberphile T-Shirts: https://teespring.com/stores/numberphile Other merchandise: https://store.dftba.com/collections/numberphile