You really need to have seen the main video for this to make sense! More links & stuff in full description below ↓↓↓ MAIN VIDEO: https://www.youtube.com/watch?v=lFQGSGsXbXE CONTINUATION: https://www.youtube.com/watch?v=qbkH_0TNdk0 AND EVEN MORE: https://www.youtube.com/watch?v=uENSO785aEI PLUS CUT FROM PART ONE: https://www.youtube.com/watch?v=hggcjvdCihc Featuring Zvezdelina Stankova - Professor of Mathematics at Mills College, Director of Berkeley Math Circle, UC Berkeley Spreading clones across a chessboard and escaping "prison" - commonly known as pebbling a chessboard. Check these papers: http://bit.ly/pebblechess1 http://bit.ly/pebblechess2 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