Cool site! When I do this trick I prefer using Bob Goddard's 'first Sunday' method [0]. It minimises the number of operations you need to do and makes it so you only need to keep track of one running total.

[0] https://firstsundaydoomsday.blogspot.com/2009/12/quick-start...

It's pretty bad form to give the doomsday algorithm and not give credit to John H. Conway who invented it. https://en.wikipedia.org/wiki/Doomsday_rule

He’s well credited in the article…

Pretty sure he was not when I posted my comment. It currently says "more on him at the end" and that bit seems not to have been written yet. Also there are two mathematicians called "John Conway" so it's good form to say "John H Conway".

Author here, good call! I credit Conway in the center of the article, the content for "more on him at the end" was hidden after reader finish the challenge in part 6. I guess it worth to show it by default, updated already.

I'd also need to thanks for Dr. Arthur Benjamin. I saw his "That math show" with my 9 years old where he introduced this Doomsday rule, I thought it was really cool and try to create some interactive tutorial for it. Would love to see if this can help other kids or adults https://www.thatmathshow.com/

he did

This is amazing! What a cool website.

V. Cool - thank you for building and sharing

Horrible AI slop. Demos are great but don't subject me to llm writing please.