Uploaded January 2019 | Updated September 2026, 2 weeks ago

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Thirdsday was created (discovered?) by Jim Propp! Read his manifesto here:
mathenchant.wordpress.com/2018/12/31/introducing-thirdsday
He's @JimPropp on Twitter: twitter.com/JimPropp

Here is James Tanton's video "How to Fold or Split Things into Thirds".
youtube.com/watch?v=G8cD5NMOMcs

Check out the Think Maths resources to help calculate the digits of a third!
think-maths.co.uk/celebrating-thirdsday

And Evelyn Lamb has done a great write-up about Thirdsday for Scientific American.
blogs.scientificamerican.com/roots-of-unity/how-to-celebrate-thirdsday

The animation was by Lucas Vieira and you can read more about it at the end of Jim Propp's post.
1ucasvb.com
mathenchant.wordpress.com/2018/12/31/introducing-thirdsday/#end1

EVE HAD HIT MAX, FOR THE SLY OLD MAN MAX HAD HID HER PET CAT, MOG, AND SHE WAS SAD BUT SHE DID NOT CRY.
By Hannah Fisher, 2018.
twitter.com/allthestations/status/1046836223225057280

CORRECTIONS
- I totally missed a “FOR” in Hannah’s short story. Thank goodness the digits still worked! First spotted by JWB_.
- Let me know if you spot anything else!


Thanks to my Patreon supports who do support these videos and make them possible. Here is a random subset:

Samuel Ytterbrink
David Lake
Lucas Werkmeister
Mark Prince
David Wagner

Support my channel and I can make more maths videos:
patreon.com/standupmaths


Music by Howard Carter
Filming and editing by Matt Parker
Design by Simon Wright


MATT PARKER: Stand-up Mathematician
Website: standupmaths.com
Maths book: wwwh.umble-pi.com
Nerdy maths toys: mathsgear.co.uk