Keep practicing how quickly and consistently can you find the correct weekday for a date.
Confidently determine the weekday of any given date, anywhere and anytime without relying on a calendar.
Enhance your mental agility by mastering the art of date-to-weekday conversion.
Be the one who casually answers when someone asks what day Christmas lands on this year.
However you like to learn — read it, drill it, or just play.
A step-by-step course: doomsdays, anchor days, leap years and more.
OpenDrill each sub-skill as a fast, focused mini-game.
OpenFind the weekday for random and historical dates.
OpenThe same five dates as everyone else, every 24 hours.
OpenLong-form articles, memory tricks and a practice plan.
OpenIt’s a method for working out the day of the week for any date — past or future — in your head, in seconds. The trick is that a handful of memorable dates each year all share the same weekday, called that year’s doomsday. Find it, and every other date is a short count away.
Try it with your own birthday below, then learn the full method.
What the Day is a side project I’ve built to help people master the Doomsday algorithm. If you’ve enjoyed using it, consider supporting its development!
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