Katie Steckles dazzles us with Mental Logs. Have a look at Brilliant (and get 20% off) here: https://brilliant.org/Numberphile More links & stuff in full description below ↓↓↓ More Katie on Numberphile: http://bit.ly/Steckles_Playlist Katie Steckles: http://www.katiesteckles.co.uk/ Those mental log sticks on Amazon: http://amzn.to/2ItpMYQ (Numberphile's affiliate link) Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science. https://www.simonsfoundation.org/outreach/science-sandbox/ And support from Math For America - https://www.mathforamerica.org/ 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 Animation and editing: Pete McPartlan 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