FRIDAY THE 13TH


STRANGE BUT TRUE: The 13th of the month is more likely to be a Friday than any other day of the week!

Why?

Thus, rather than cycling through the 7 different 400-year cycles, in which case the 13th would be evenly distributed across all weekdays, we are locked into a single cycle. In this cycle, the 13th lands on a Friday one more time than on any other day of the week.


Tevian Dray
tevian at math dot oregonstate dot edu