The International Mathematical Union is trying to get UNESCO to make March 14, commonly known as π Day, the International Day of Mathematics.
You're reading: Posts Tagged: Pi Day
“π – It’s Complicated” – a talk I gave on Pi Day 2016 at Ustinov College Café Scientifique
I was invited to give a talk for Ustinov College’s Café Scientifique on π Day this year. The turnout wasn’t great and I put quite a bit of effort into the slides, so I wanted to put it online. I’ve finally got hold of the recording, so here it is. Unfortunately they didn’t set the camera’s exposure properly, making the screen illegible, so you’ll probably want to follow along with the slides in another window.
I tried to come up with a way of writing today’s date as a multiple of π Day, but couldn’t make it work. However, I did realise that Halloween (31/10) is the best approximation to π between now and the next π day (I think). Sπooky!
Ohioans measure a really big π

Ohio State University mathematician Niles Johnson got in touch on Friday to tell us that our π Approximation Challenge last year had inspired him to hatch an audacious plan to measure a really big π.
The word ‘geometry’ is derived from the Greek for ‘measurement of land’, and Dr. Johnson took that quite literally: he wanted to measure the Great Circle Earthworks in Heath, Ohio; a part of the Newark Earthworks (not their original name) built over 2,000 years ago.
Improbable John Conway/Pizza Hut collaboration for π day
John Conway, here pictured browsing the character table of $Fi_{23}$
Restaurant chain Pizza Hut in the US have announced a promotion for “Pi Day” on March 14, involving an unlikely partnership with renowned group-theorist, Life-wrangler and apparent pizza-lover John Conway. (Apparently, pizza and pie are somehow linked in America. It is probably best not to worry about this.)
Featuring on their blog as the inaugural post under the optimistic tags ‘math‘ and ‘John Conway‘, they explain that three maths puzzles set by Conway will be posted on Pi Day, “varying in level of difficulty from high school to Ph.D. level”. Residents of the 48 contiguous US states can leave their answers in the comments when the puzzles are posted, and the winners receive a 3.14-year supply of pizza (or, as the rules clarify, a somewhat more prosaic $1600 Pizza Hut gift card).
Obviously we will have to wait for the questions to be unveiled to be able to judge the appropriate level of excitement for this promotion, but with Conway involved, no maths-is-really-hard nonsense in the blog post, and not a formula for the perfect anything in sight, things are looking promising for a nice bit of harmless maths/poor childhood diet fun.
More information
Pizza Hut partners with mathematician John H. Conway for National Pi Day math contest – the blog post announcing the competition
John Conway on Wikipedia
A geometrical approximation for π
If you were paying very close attention last week, you’ll have noticed my attempt to come up with an estimate of π, geometrically, as part of The Aperiodical’s π Day challenge (even if it’s not really π Day):
Oo, my second effort at estimating π came to 3.14151, correct to 0.003%! cc @aperiodical pic.twitter.com/2vuvys0mka
— Colin Beveridge (@icecolbeveridge) March 10, 2015
π and constrained writing
It’s a tool; a ratio, providing us simple rules for doing circular estimates. Admired regularly – and we all remember that today’s pi! Hooray! Let’s eat pie.
You may have noticed that the first paragraph of this article was immensely poorly written, and didn’t sound like good writing at all. And you’d be right – except writing it wasn’t easy as you’d think. I’ve written it under a constraint – that is, I’ve picked an arbitrary rule to follow, and have had to choose my words carefully in order to do so.
Interesting π Esoterica
My way of celebrating π day is to rummage through my trove of obscure writings and dig up some interesting esoterica on the subject of that constant. Here’s what I found.
In case you’re new to this: every now and then I encounter a paper or a book or an article that grabs my interest but isn’t directly useful for anything. It might be about some niche sub-sub-subtopic I’ve never heard of, or it might talk about something old from a new angle, or it might just have a funny title. I put these things in my Interesting Esoterica collection on Mendeley. And then when I’ve gathered up enough, I collect them here.