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TIL that 4/4, 6/6, 8/8, 10/10 and 12/12 all fall on the same day in every year ever. Trying to teach my brain the doomsday algorithm to mentally do the math of what day of the week for any given date. This above is just one input. Numbers are fun!

Just browsing

@justbrowsing72.bsky.social

14 Aug

This feels like it cannot be true, leap years would mess it up even if it was always true for non-leap years.

dottn.no

@dottn.no

All the dates mentioned are after leap day, so this would hold even in Leap years.

14/8/26, 8:39 pm0 reposts1 like

Josh Sternberg

@joshsternberg.com

14 Aug

correct. yep! january is the 3rd; 4th on a leap year; february is the 28th; 29th on a leap year; march is the 14th (pi day! ) and for the odd months: 5/9 and 9/5; 7/11 and 11/7. so these are all called "doomsday days"

Just browsing

@justbrowsing72.bsky.social

15 Aug

I googled doomsday days and now I understand! I thought you meant that 4/4 was always a Tuesday (or whatever) in every year ever, like last year, then this year, etc. But you meant those dates fall on the same weekday as each other in the same year for any given year. Hence my confusion!