alt.hn

8/24/2026 at 2:57:45 PM

Show HN: How to Mentally Calculate the Day of the Week for Any Date

https://tinkerandsee.com/weekday/

by yang140

8/25/2026 at 1:21:31 AM

This is amazing! What a cool website.

by mattdeboard

8/24/2026 at 5:19:20 PM

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

by seanhunter

8/24/2026 at 5:31:42 PM

He’s well credited in the article…

by atestu

8/24/2026 at 6:26:48 PM

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".

by seanhunter

8/24/2026 at 7:17:50 PM

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/

by yang140

8/24/2026 at 10:18:10 PM

he did

by anas008

8/24/2026 at 11:30:43 PM

V. Cool - thank you for building and sharing

by navaed01

8/25/2026 at 2:39:33 AM

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

by _dark_matter_