Dr Hannah Fry discusses Secret Santa, anonymity and derangements. And a better way to do it. More links & stuff in full description below ↓↓↓ More Hannah on Numberphile: http://bit.ly/hannah_vids Hannah's co-written Xmas book: http://amzn.to/2g8mIn6 Hannah's love/math book: http://bit.ly/frylovebook Numberphile poster: https://store.dftba.com/products/numberphile-poster Graham's Number T-Shirt: https://store.dftba.com/collections/numberphile/products/grahams-number-shirt Other Numberphile T-Shirts: null Hannah on Objectivity: https://www.youtube.com/watch?v=ayzKlPIcRKU Support us on Patreon: http://www.patreon.com/numberphile 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 Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile Videos by Brady Haran 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: null Other merchandise: https://store.dftba.com/collections/numberphile