mscroggs.co.uk
mscroggs.co.uk

subscribe

Blog

Happy -3+π+√3 Approximation Day!

 2020-07-29 
A week ago, it was 22 July: Pi Approximation Day. 22/7 (22 July in DD/M format) is very close to pi, closer in fact than 14 March's approximation of 3.14 (M.DD).
During this year's Pi Approximation Day, I was wondering if there are other days that give good approximations of interesting numbers. In particular, I wondered if there is a good 2π (or τ) approximation day.
π is close to 22/7, so 2π is close to 44/7—but sadly there is no 44th July. The best approximation day for 2π is 25th April, but 25/4 (6.25) isn't really close to 2π (6.283185...) at all. The day after Pi Approximation Day, however, is a good approximation of 2π-3 (as π-3 is approximately 1/7). After noticing this, I realised that the next day would be a good approximation of 3π-6, giving a nice run of days in July that closely approximate expressions involving pi.
After I tweeted about these three, Peter Rowlett suggested that I could get a Twitter bot to do the work for me. So I made one: @HappyApproxDay. Since writing this post, Twitter broke @HappyApproxDay by changing their API, but the bot lives on on Mathstodon (@HappyApproxDay@mathstodon.xyz) and Bluesky (@happyapproxday.bsky.social).
@HappyApproxDay is currently looking for days that approximate expressions involving π, τ, e, √2 and √3, and approximate the chosen expression better than any other day of the year. There are an awful lot of ways to combine these numbers, so @HappyApproxDay@mathstodon.xyz looks like it might be tooting quite a lot...
Edit: Added Mastodon and Bluesky links
×4      ×4      ×4      ×5      ×6
(Click on one of these icons to react to this blog post)

You might also enjoy...

Comments

Comments in green were written by me. Comments in blue were not written by me.
June the 28th (6.28) isn't too bad for 2 Pi.
steve
×4   ×6   ×2   ×2   ×2     Reply
 Add a Comment 


I will only use your email address to reply to your comment (if a reply is needed).

Allowed HTML tags: <br> <a> <small> <b> <i> <s> <sup> <sub> <u> <spoiler> <ul> <ol> <li> <logo>
To prove you are not a spam bot, please type "w" then "i" then "d" then "t" then "h" in the box below (case sensitive):

Archive

Show me a random blog post
 2026 

May 2026

World Cup stickers 2026

Apr 2026

A new puzzle every day
Mixing Wordle with other games

Feb 2026

Christmas (2025) is over
 2025 

Dec 2025

Christmas card 2025

Nov 2025

Christmas (2025) is coming!

Sep 2025

The partridge puzzle

Aug 2025

TMiP 2025 puzzle hunt

Jun 2025

A nonogram alphabet

Mar 2025

How to write a crossnumber

Jan 2025

Christmas (2024) is over
Friendly squares
 2024 

Dec 2024

A regular expression Christmas puzzle
Christmas card 2024

Nov 2024

Christmas (2024) is coming!

Feb 2024

Zines, pt. 2

Jan 2024

Christmas (2023) is over
 2023 
▼ show ▼
 2022 
▼ show ▼
 2021 
▼ show ▼
 2020 
▼ show ▼
 2019 
▼ show ▼
 2018 
▼ show ▼
 2017 
▼ show ▼
 2016 
▼ show ▼
 2015 
▼ show ▼
 2014 
▼ show ▼
 2013 
▼ show ▼
 2012 
▼ show ▼

Tags

cambridge coins advent calendar bots world cup recursion european cup sound graphs golden ratio regular expressions crosswords hexapawn gerry anderson frobel flexagons tmip zines game show probability turtles coventry bempp hats radio 4 national lottery weak imposition geometry dinosaurs statistics pokémon alphabets dates weather station phd sport mathslogicbot puzzles pi approximation day preconditioning partridge puzzle tetris logs errors news speed anscombe's quartet palindromes mean fence posts plastic ratio christmas bodmas nonograms simultaneous equations dataset raspberry pi runge's phenomenon matrices misleading statistics geogebra signorini conditions probability inverse matrices asteroids a gamut of games datasaurus dozen big internet math-off estimation electromagnetic field rugby map projections fractals propositional calculus php noughts and crosses ucl tennis exponential growth manchester science festival finite element method platonic solids trigonometry python gaussian elimination bubble bobble realhats numerical analysis determinants matt parker harriss spiral london underground reuleaux polygons folding tube maps latex countdown pizza cutting wave scattering curvature folding paper graph theory wool mathsjam binary matrix of minors braiding captain scarlet kings chalkdust magazine friendly squares data visualisation correlation programming thirteen triangles books javascript crochet draughts stickers crossnumbers approximation matrix of cofactors machine learning reddit databet boundary element methods quadrilaterals crossnumber talking maths in public sobolev spaces pi hannah fry golden spiral christmas card craft interpolation inline code dragon curves mathsteroids rhombicuboctahedron pythagoras gather town game of life london games nine men's morris hyperbolic surfaces martin gardner computational complexity football light pokémon wordle chebyshev bluesky youtube numbers newcastle standard deviation royal institution wordle oeis pascal's triangle matrix multiplication manchester stirling numbers pac-man arrangement puzzles arithmetic warwick finite group the aperiodical chess people maths menace guest posts squares logo 24 hour maths video games royal baby error bars final fantasy cross stitch rust fonts polynomials convergence accuracy edinburgh logic sorting kenilworth live stream ternary go data

Archive

Show me a random blog post
▼ show ▼
© Matthew Scroggs 2012–2026