Show HN: How to mentally calculate the day of the week for any date (tinkerandsee.com)

54 points by yang140 15 hours ago

12 comments:

by santah 9 minutes ago

Awesome site and guide, I just don't understand why all dates have the month in front of the date.

Isn't this very confusing to anyone outside US?

I get why it defaulted to this format, but in this day and age - it's trivial to automatically adjust it to the user's localization / preferences.

by Vishal_Max 24 minutes ago

Never thought of this , actually enjoyed learning it. Now it is time to surprise my friends.

by mrheosuper an hour ago

>The trick = nearest squad date → leftover → walk from the Doomsday.

When i do the 31/OCT, the solution show 10/10 as nearest squadday, i though 11/7 is the nearest ?

by zeech 8 hours ago

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...

by seanhunter 12 hours ago

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 atestu 12 hours ago

He’s well credited in the article…

by seanhunter 11 hours ago

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 yang140 10 hours ago

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 anas008 7 hours ago

he did

by mattdeboard 4 hours ago

This is amazing! What a cool website.

by navaed01 6 hours ago

V. Cool - thank you for building and sharing

by _dark_matter_ 3 hours ago

[flagged]

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