238th Carnival of Mathematics

Wow! It's the 238th Carnival of Mathematics organized by Aperiodical. This has been a fun month with lots of submissions and lots of beautiful math art. To start let's jump into the number 238 itself.

238 is:

• 2 × 7 × 17.
• the sum of the first 13 primes.
• a "triprime" (the product of three primes).
• I asked and was not disappointed by the Mathstodon community:
  • Uranium-238 is the most common isotope of uranium (From Rich Holmes)
  • 2^3 = 8 (from DR Ms KAT and Maya Zimmerman)
  • Year of the six emperors? CE, Rome, three unique Gordians as well! (from @Mycotropic)
  • For those of you that have a birth minute of 02:38 - happy birth minute - I will post this at 02:38 at some time in the world. You can celebrate this minute every day) (from Mark Dominus via Ranjit)
  • "EE" in Hex (from Joe Crawford)
  • WOW - there is a website called Number Gossip! with a page fore 238. (Thank you Charlotte Aten!)
  • "It's the number ways to label a connected graph with 5 nodes that stays connected if you remove a node. No, that wasn't a favorite fun fact before just now; I just did an OEIS/Wikipedia dive." (from Alexandre Muñiz)
• The complete graph of K238 has 28,203 edges (see the feature image).
• untouchable (see numberphile) (and extremely slow codepen to play with below):

See the Pen untouchable numbers by Sophia (fractal kitty) (she/her) (@fractalkitty) on CodePen.

In addition to scraping OEIS and the internet for this number, I put a 238-celled Voronoi diagram on a sphere to confirm that the most boring of numbers can be fun:

And now the Carnival for March 2025:

• The month kicked off with Ayliean's #MathArtMarch and it was inspiring! On BlueSky check out the hashtag and the gallery of beautiful works from around the world. There is crochet, coding, painting, beads, structure and more - this community is amazing!

Mathy Blog Posts and Activities:

• Peter Cameron has a thoughtful blog post on Compactness, Memories of CFSG, and tips for Defending Research Against Government Censorship.
• There is a wonderful post on polyominoes on the Puzzle Zapper blog.
• On The Universe of Discourse, Mark Dominus posted on a modern presentation of Peano Axioms.
• On Math ∩ Programming, Jeremy Kun has some exciting news about a new book – Practical Math for Programmers.
• Brian Clegg's blog, Now Appearing, has an interesting post on the Monty Hall Problem.
• The Computational Complexity blog has a post on a Failure to Communicate.
• Karen Campe continued her very visual Go For Geometry Series.
• Amédée d’Aboville did a second post on Group Theory With Zoombinis where these little Zoombinis like "jamming, alchemy, and transmuting".
• Ed Vogel always shares the most enjoyable activities with Soma cubes, pentominoes and more. This month he has a fun activity with a KANOODLE toy.
• Pi day was celebrated with this amazing video by Stand-Up Maths

Mathstodon:

There are hundreds of amazing posts on Mathstodon; here are just a couple:

• Christian Lawson-Perfect updated the infinite stream of Pi digits.
• Colin Beveridge had an insightful post on estimations in a Guardian article.

In the News:

• Aperiodical's news round up
• Quanta Magazine has an article on A New Proof Smooths Out the Math of Melting.
• Scientific American: The 9 Unsolved Mysteries Mathematicians Can’t Stop Thinking About.
• CUNY's Mathematical Art Digital Exhibition (MADE) Exhibition site is up! Check out all of the beautiful art and musings from mathematicians from around the world. I was honored to be part of this exhibition with one of my 2022 Mathober pieces.