Guides
Everything you need to learn the Doomsday algorithm and calculate the weekday for any date in your head.
What Is the Doomsday Algorithm?
6 min readWhere the method came from, the one idea it is built on, and why it works.
Read guide →How to Calculate the Day of the Week for Any Date in Your Head
8 min readThe full method, broken into five steps, with a worked example you can follow.
Read guide →Doomsday Algorithm Memory Tricks and Mnemonics
7 min readAnchor-day and doomsday-date mnemonics, plus the shortcuts that build speed.
Read guide →A Two-Week Practice Plan for Mental Calendar Math
6 min readA day-by-day plan that turns the theory into fast, reliable recall.
Read guide →