Uploaded May 2019 | Updated September 2026, 2 weeks ago

---

Here is the original Fermat's Library tweet.
twitter.com/fermatslibrary/status/1052544515632959488

We make Think Maths teaching resources to go with Stand-up Maths videos. For this one we have a cheat sheet to an algebraic proof.
think-maths.co.uk/standupmaths-videos?yt-calculator-rectangles#calculator-rectangles

Many people are asking for the gif. It’s available in different forms in various places online.
tenor.com/view/matt-parker-parker-square-mindblown-maths-math-gif-11856384
imgur.com/gallery/HyPfz

Originally a homage to the Tim and Eric gif. From this video: youtu.be/LhlqCJjbEa0

The ticking sound in the video was from here.
freesound.org/people/KentVideoProduction/sounds/159723

CORRECTIONS
- I did not properly think through the hexadecimal example. I meant that any such digits on a base-10 calculator would give multiples of 11. On a true hexadecimal calculator you would get multiples of 17 (or any n+1 for base-n). First spotted by MasterHigure.
- 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:

Igor Bogoslavskyi
James Williams
Magesh Jayapandian
David Lake
Chris W West

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