James Clewett graphs one of his favourite books and explains the significance of 400.
“Turn to 400″ Kickstarter: http://kck.st/T2ND32 ends Nov 30, 2012 – Numberphile is not involved and receives no benefit – but tell Sean we sent you! 
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
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Videos by Brady Haran
Brady’s other channels include:
http://www.youtube.com/periodicvideos (Chemistry stuff)
http://www.youtube.com/sixtysymbols (Physics and astronomy)
http://www.youtube.com/DeepSkyVideos (Space stuff)
http://www.youtube.com/nottinghamscience (Science and behind the scenes)
http://www.youtube.com/foodskey (Food science)
http://www.youtube.com/BackstageScience (Big science facilities)
http://www.youtube.com/favscientist (Favourite scientists)
http://www.youtube.com/bibledex (Academic look at the Bible)
http://www.youtube.com/wordsoftheworld (Modern language and culture)
http://www.youtube.com/PhilosophyFile (Philosophy stuff)
http://www.youtube.com/PsyFile (Psychology stuff)