Welcome one and all! Come on in and have a ball. 159 is semiprime and that's just fine.

Lucky that I'm hosting this, or is it just that 159 is lucky. How do you get lucky? Start with the counting numbers. Delete every 2nd number, leaving 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45... odd. The 2nd number remaining is 3, so delete every 3rd number, leaving 1 3 7 9 13 15 19 21 25 27 31 33 37 39 43 45... now that's interesting in and of itself. Next delete every 7th number, leaving 1 3 7 9 13 15 21 25 27 31 33 37 43 45 ...; now delete every 9th number; etc. How far do we have to go before we know 159 is lucky? Does knowing 151 is the previous lucky number help? Interesting to look at the gaps in each step, and the cutlist for each step.Pat Bellew's 159 facts are that 159 is the sum of 3 consecutive prime numbers (which?) and can be written as the difference of two squares in two different ways (don't you want to find them?).

He also has that __ __ •159 = __ __ __ __ using all 9 nonzero digits. Of course, you can brute force it, but can you deduce this digitally complete product?

What #playfulmath have you seen this month? Here's some of what I have noticed.

September started with Math on a Stick in full swing. Doesn't get more playful than that!

Katie Steckles and Jimi went over the math in the Spider-Man No Way Home end credits. I lost my mind when watching it in the theatre, and am so glad someone's sharing it. SO MANY MC Escher references.

And as if the visuals weren't sufficient, the song is De La Soul's great cover of the Schoolhouse Rock classic, Three is a Magic Number.as yet undiscovered unpentennium |

The Erikson Institute is a great source for early math insights, and here they cover four playful number books.

Charlotte Sharpe shared a quick, rich early math game with dice and subitizing cards.

Michael Minas & helpers are back with an inequality game, Big Bad Wolf and the Three Little Pigs.

Australian Math Circles shared this online interactive math game with lots of nice number recognition and sense images.

Libo Valencia tweeted about his class playing this angle game, Daniel Mentrard's Polar Battleship.

He also shared his daughters catmathart... a perfect transition to the next section.

Zarah Hussain shared her icosahedron statue on public display in London.

Paula Beardell Krieg is always busy with something creative and beautiful. For instance, her Rather Strange Solids. (But while you're there, poke around.)

Sophia Wood does programming, teaching and art. Her latest bird is perched on an unorientable branch...

Sam Hartburn sang to some Ayliean artwork for a recent Clopen Mic Night.

SimonLav with a Marvel-ous Desmos animation.

David Reimann nods to Magritte with this piece, related to his Bridges article.

Last but not least, I'm very happy to be a part of David Coffey's newest project: the Teaching Like Ted Lasso Podcast. Episode 1 is out, and it's on... PLAY! Check the show notes for scoonches of resources on play in math class.

As long as I'm on the pitch... just after this post on this blog are some very fun, well developed math games from my students.

And what's next? #Mathober! Sophia Wood has put together a list of prompts.

Each day there's a theme. Share a bit of math, a doodle, a comic, some art on the theme. Play along one day, or all 31. Tweet or send it to Sophia or myself and we'll share.
Wonderful John, as your work so often is.

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