A bit extra from the main video: https://www.youtube.com/watch?v=hHG8io5qIU8 Hannah Fry has a new book coming: https://amzn.to/2J6oCph (US) or https://amzn.to/2KVfXDD (UK) Objectivity: http://bit.ly/Objectivity (please subscribe!) More Hannah on Numberphile: http://bit.ly/hannah_vids Some extra out-take video from Hannah's stint behind the camera is available to Patrons!!! https://www.patreon.com/posts/19022716 NUMBERPHILE Website: http://www.numberphile.com/ Numberphile on Facebook: http://www.facebook.com/numberphile Numberphile tweets: https://twitter.com/numberphile Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile Videos by Brady Haran Support us on Patreon: http://www.patreon.com/numberphile Brady's videos subreddit: http://www.reddit.com/r/BradyHaran/ A run-down of Brady's channels: http://www.bradyharan.com/ Sign up for (occasional) emails: http://eepurl.com/YdjL9