66 | Tiger Woods shoots a 66, his best performance since 2011, July 21, 2018

https://www.usatoday.com/story/sports/golf/2018/07/21/open-championship-tiger-woods-third-round-carnoustie/812513002/

Today was a great day for a 66...

7/21/2018 = 7+21+20+18 = 66

66 is the 11th triangular number, and this is his best round at a major since 2011, emphasis on '11.

http://www.espn.com/golf/story/_/id/24159729/2018-open-why-worth-rooting-tiger-woods-win-open-carnoustie