## You sank my battleship... with probability!

Battleship Probability Calculator by C. Liam Brown. Finds the best squares to try during the game.
posted by Wolfdog on Sep 17, 2015 - 14 comments

## Inspired by mathematical theorems or open problems...

Conveyer Belt Font. More mathematical and puzzle fonts/typefaces you can play with in your browser. Read about them in the article Fun with Fonts: Algorithmic Typography. [PDF]
posted by Wolfdog on Sep 8, 2015 - 6 comments

## a(n)=a(n−1)+gcd(n,a(n−1)).

Go ahead: Press the button. A number is printed on the tape. Press again and another number appears. Keep going. A few more. Notice anything special about those numbers? The sequence begins: 5, 3, 11, 3, 23, 3, 47, 3, 5, 3, 101, 3, 7, 11, 3, 13, 233, 3, 467, 3, 5, 3, . . .
posted by Wolfdog on Sep 6, 2015 - 25 comments

## "Their little heads are exploding"

Mrs. Nguyen’s Prestidigitation From a set of 1 through 9 playing cards, I draw five cards and get cards showing 8, 4, 2, 7, and 5. I ask my 6th graders to make a 3-digit number and a 2-digit number that would yield the greatest product... and somehow we end up with lacing diagrams and Python. (The original post on Fawn Nguyen's blog)
posted by Wolfdog on Jun 22, 2015 - 18 comments

## Time with class! Let's Count!

I want to demonstrate how amazing combinatorial explosion is! Please don't stop me.  An animation about numbers that get large. It has a happy ending and possibly even a moral.
posted by Wolfdog on Jun 12, 2015 - 21 comments

Alcazar is a neat little path-finding logic game. There are also printable puzzles, strategy tips and metapuzzles to be had.
posted by Wolfdog on May 2, 2015 - 15 comments

## No Pentagons

Imperfect Congruence - It is a curious fact that no edge-to-edge regular polygon tiling of the plane can include a pentagon ... This website explains the basic mathematics of a particular class of tilings of the plane, those involving regular polygons such as triangles or hexagons. As will be shown, certain combinations of regular polygons cannot be extended to a full tiling of the plane without involving additional shapes, such as rhombs. The site contains some commentary on Renaissance research on this subject carried out by two renowned figures, the mathematician-astronomer Johannes Kepler and the artist Albrecht Dürer.
posted by Wolfdog on Jan 14, 2015 - 16 comments

## "Science is when you think a lot."

Two enjoyable chapters [PDF, 33 pages] from the book Math from Three to Seven: The Story of a Mathematical Circle for Preschoolers. "This book does not purport to show you how to create precocious high achievers. It is just one person's story about things he tried with a half-dozen young children."
posted by Wolfdog on Dec 29, 2014 - 11 comments

## Rainy Day

Pencil and Paper Games is devoted to games you can play with nothing more than a pencil and a piece of paper (some of which can be played on the site, for those who do not have access to a pencil and paper, or remember what those are.)
posted by Wolfdog on Nov 26, 2014 - 11 comments

## 100 Years of Martin Gardner!

In Honor of the Centennial of Martin Gardner's birth (October 21, 1914), we've lined up Thirty-One Tricks and Treats for you: Magazine articles, new and classic puzzles, unique video interviews, and lots more.The Nature of Things / Martin Gardner [46min video] ✤ The College Mathematics Journal, January 2012 dedicated to Gardner with all articles readable online.
posted by Wolfdog on Oct 23, 2014 - 32 comments

## It's just a jump to the ... well, in any legal direction really

The Peg Solitaire Army is a problem spun off from a classic recreation, and yet another example of the golden ratio turning up where you least expect it. If you want to look at the game more deeply, George Bell's solitaire pages are the ne plus ultra: There's more about the solitaire army (and variants), ...
posted by Wolfdog on Aug 15, 2014 - 6 comments

## do while !glory

Welcome to Al Zimmermann's Programming Contests. You've entered an arena where demented computer programmers compete for glory and for some cool prizes. The current challenge is just about to come to an end, but you can peruse the previous contests and prepare for the new one starting next month.
posted by Wolfdog on Aug 14, 2014 - 11 comments

## Piecewise linear functions are magic

Graphing Calculator: Creative Art
posted by Wolfdog on Apr 30, 2014 - 11 comments

## "I really like polyhedra."

Polyhedra and the Media - On the new polyhedra of Schein and Gayed, and mathematical journalism.
posted by Wolfdog on Mar 11, 2014 - 20 comments

## The one that is the smaller is the larger

The Teaching of Arithmetic: The Story of an experiment. In the fall of 1929 I made up my mind to try the experiment of abandoning all formal instruction in arithmetic below the seventh grade and concentrating on teaching the children to read, to reason, and to recite - my new Three R's. And by reciting I did not mean giving back, verbatim, the words of the teacher or of the textbook. I meant speaking the English language. I picked out five rooms - three third grades, one combining the third and fourth grades, and one fifth grade. I asked the teachers if they would be willing to try the experiment.
posted by Wolfdog on Mar 8, 2014 - 18 comments

## That’s why it doesn’t matter if God plays dice with the Universe

Discovering Free Will (Part II, Part III) - a nice discussion of the Conway-Kochen "Free Will Theorem".
posted by Wolfdog on Mar 4, 2014 - 92 comments

## It's Action, Reaction, Diffusion Interaction

Reaction-diffusion reactions used to design housewares, puzzles, and more. If you want to experiment yourself, you might get some ideas from the demos at WebGL Playground or you might use this brief intro as a jumping-off point.
posted by Wolfdog on Feb 23, 2014 - 13 comments

## Visual Patterns.

Visual Patterns. Here are the first few steps. What's the equation?
posted by Wolfdog on Feb 18, 2014 - 19 comments

## The Hierarchy of Hexagons

The Hierarchy of Hexagons. School geometry seems to me one of the most lifeless topics in all of mathematics. And the worst of all? The hierarchy of quadrilaterals.
posted by Wolfdog on Feb 11, 2014 - 36 comments

## The strange case of The Pigeon-hole Principle

It's Saturday; why not think about the pigeonhole principle? Here are problems and more problems and what you might call a problem with the principle itself as it is often stated.
posted by Wolfdog on Nov 10, 2012 - 41 comments

## The Angel Problem

The Angel Problem. The Angel and the Devil play a game on an infinite chess board...
posted by Wolfdog on Feb 16, 2012 - 37 comments

## Number A Day

NumberADay - Every working day, we post a number and offer a selection of that number’s properties.
posted by Wolfdog on Jan 11, 2012 - 30 comments

## Morpion Solitaire

Morpion Solitaire is a very simple pencil-and-paper, line-drawing game for which the best possible score is not known! New records are still being set.
posted by Wolfdog on Jan 8, 2012 - 21 comments

## Machines of Paper and Wood

Building a Computer 1: Numerals - recently my kids have been asking me about how computers work. I like to give in-depth answers to such questions, so we set out on a quest to understand how they work... Follow-up parts 2 3 4 5 6 7 8 9 10 11 12 13 14 15.
posted by Wolfdog on Oct 20, 2011 - 17 comments

## Growing a hyperdodecahedron

This short computer graphics animation presents the regular 120-cell: a four dimensional polytope composed of 120 dodecahedra and also known as the hyperdodecahedron or hecatonicosachoron.
posted by Wolfdog on Aug 2, 2011 - 29 comments

posted by Wolfdog on Jul 19, 2011 - 6 comments

## Then you wouldn't have to say "QED", 'cause I'd already know

A thread full of proofs without words at MathOverflow and quite a lot more of them courtesy of Google Books.
posted by Wolfdog on Jul 18, 2011 - 22 comments

## The plot isn't great, but the plots are pretty good.

The OEIS Movie is simply a slideshow of one thousand plots from the Online Encyclopedia of Integer Sequences, at two plots per second with sequence-generated music.
posted by Wolfdog on Dec 2, 2010 - 12 comments

## Snail Ball

The Geometry of the Snail Ball [pdf] - an interesting article (with some DIY advice at the end) about a toy shop curiosity you may have encountered.
posted by Wolfdog on Nov 16, 2010 - 25 comments

## I don't know much about math, but I know what I like.

Plus magazine has compiled all their articles on mathematics and the arts into one handy-dandy page full of highly enjoyable articles ranging from limericks and screeching violins to the restoration of frescoes.
posted by Wolfdog on May 16, 2010 - 3 comments

## Moving Remy in Harmony

Moving Remy in Harmony - Pixar's Use of Harmonic Functions.
posted by Wolfdog on Apr 15, 2010 - 38 comments

## Mathematics Illuminated

Mathematics Illuminated is a set of thirteen surveys in varied topics in mathematics, nicely produced with video, text, and interactive Flash gadgets for each of the topics.
posted by Wolfdog on Apr 14, 2010 - 8 comments

## A glorified geometry with superimposed computational torture

Trigonometric Delights. This book is neither a textbook of trigonometry—of which there are many—nor a comprehensive history of the subject, of which there is almost none. It is an attempt to present selected topics in trigonometry from a historic point of view and to show their relevance to other sciences. It grew out of my love affair with the subject, but also out of my frustration at the way it is being taught in our colleges.
posted by Wolfdog on Mar 24, 2010 - 18 comments

## All Gnytte Long

The Sexaholics of Truthteller Planet - yes, it's one of those rotten logic problems, one of many that can be found at Tanya Khovanova’s Math Guide to the MIT Mystery Hunt.
posted by Wolfdog on Jan 13, 2010 - 21 comments

## Calculus of Averages

Calculus of Averages - Newton and Archimedes did not possess this knowledge. No mathematics professor today can provide this knowledge and depth of understanding. Author John Gabriel maintains a blog, Friend of Wisdom, and contributes articles such as Are real numbers uncountable? to Google's Knol project.
posted by Wolfdog on Jan 8, 2010 - 78 comments

## Delightful Puzzles

A gathering of puzzles including many old chestnuts but also perhaps one or two you haven't met before.
posted by Wolfdog on Dec 16, 2009 - 29 comments

## Who is Alexander Grothendieck?

Who is Alexander Grothendieck? [PDF] This lecture is concerned not with Grothendieck's mathematics but with his very unusual life on the fringes of human society. In particular, there is, on the one hand, the question of why at the age of forty-two Grothendieck first of all resigned his professorship at the Institut des Hautes Etudes Scientifiques (IHES); then withdrew from mathematics completely; and finally broke off all connections to his colleagues, students, acquaintances, friends, as well as his own family, to live as a hermit in an unknown place. On the other hand, one would like to know what has occupied this restless and creative spirit since his withdrawal from mathematics.
posted by Wolfdog on Aug 17, 2008 - 31 comments

## Big book of algorithms

If you could use a great big free handbook of discrete math and algorithms, Jörg Arndt's fxtbook wants to be your friend. Plain text table of contents to whet your appetite.
posted by Wolfdog on Mar 5, 2008 - 11 comments

## There's definitely a method to my madness. Definitely.

Lightning calculator and "mathemagician" Art Benjamin goes through his paces in a 15 minute video.
posted by Wolfdog on Dec 19, 2007 - 32 comments

## Squaring the square

Nowhere-neat tilings are actually pretty neat. We all know you can't "square the circle", but do you know the story of squaring the square? (And by the way, even if you can't construct π with a ruler and compass, you can come awfully close without too much work.)
posted by Wolfdog on Dec 4, 2007 - 10 comments

## Symmetry. Shakespeare. Islamic medicine. Creative writing challenges.

Symmetry. Shakespeare. Islamic medicine. Creative writing challenges. Four podcast series from University of Warwick.
posted by Wolfdog on Nov 18, 2007 - 2 comments

## 3 is an odd prime, 5 is an odd prime, 7 is an odd prime, 9 is a very odd prime...

The Prime Game is not really much of a game, but it is a neat & little-known fact about the decimal representation of prime numbers.
posted by Wolfdog on Jul 10, 2007 - 24 comments

## ...the models live in the curved space of the hypersphere...

Here are some beautifully rendered views of polytopes, and a few more. The rendering program, Jenn 3D, is free and downloadable, (OS X, Linux, Win) and includes some really dazzling fly-about and camera effects as well as tons of high-dimensional models to explore. There's also a mind-boggling possibility of playing Go on boards in projective space. Via the Math Paint blog, which leads to other interesting places...
posted by Wolfdog on Jun 2, 2007 - 13 comments

## Snakes, in my heart-blood warm'd, that sting my heart!

SlitherLink - a little spatial-numerical puzzle. Here's a better exposition of the rules from the puzzle's inventors, and another collection of puzzles. Oh, and a little survey of other sneaky, snaky puzzles.
posted by Wolfdog on May 31, 2007 - 18 comments

## Every spherical football is a branched cover of the standard one.

Bending a soccer ball - mathematically. Found via Ivars Peterson's short exposition on Braungardt and Kotschick's The Classification of Football Patterns [pdf, technical].
posted by Wolfdog on Aug 17, 2006 - 18 comments

## Mathematical imagery by Jos Leys.

Sphere and circle arrangements, the Droste effect, and more: mathematical imagery by Jos Leys. The Droste effect article is informative, too.
posted by Wolfdog on Jun 29, 2006 - 8 comments

## Sarong Theorem Archive

The Sarong Theorem Archive is the premier online repository for pictures of mathematicans in sarongs proving theorems.
posted by Wolfdog on Feb 28, 2006 - 24 comments

## Euler? I never even met her!

Project Euler is a running contest of programming challenges to hone your algorithm skills. "Each problem is designed according to a 'one-minute rule', which means that although it may take several hours to design a successful algorithm with more difficult problems, an efficient implementation will allow a solution to be obtained on a modestly powered computer in less than one minute."
posted by Wolfdog on Aug 20, 2005 - 11 comments

## Just filling space

The Spidron is an interesting geometric construction that seems to lend itself to folding, dissection, and space-filling in two and three dimensions.
posted by Wolfdog on Jul 17, 2005 - 9 comments

## No, I'm a frayed knot

Michael Hutchings' rope trick and Dylan Thurston's two-handed knot-drawing sk1llz. Did you need to kill some time practicing pointless skills today?
posted by Wolfdog on May 6, 2005 - 12 comments

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