What's special about 277777788888899? - Numberphile

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Matt Parker discusses multiplicative persistence. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) Extra footage: https://youtu.be/E4mrC39sEOQ Matt's new book is Humble Pi: http://bit.ly/Humble_Pi More Matt videos on Numberphile: http://bit.ly/Matt_Videos The Multiplicative record holders: https://oeis.org/A003001 More info: http://mathworld.wolfram.com/MultiplicativePersistence.html Hear Matt on the Numberphile podcast... http://bit.ly/Numberphile_Pod_Playlist More links & stuff in full description below ↓↓↓ 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 Patreon: http://www.patreon.com/numberphile Numberphile T-Shirts: https://teespring.com/stores/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