The best place to sit in a "suicide circle" if you really don't want to die

Math problems are more interesting when they are posed as horror stories.

The Josephus Problem gets its name from Titus Flavius Josephus, a first-century Jewish scholar.

The story goes that he was with 40 other soldiers when they were surrounded by conquering Romans - imagine that scene in Games of Thrones, where Ramsay Bolton's men trap Jon Snow's army in a tight circle and start moving in. Rather than give themselves up, the soldiers decided to commit suicide en mass, but by killing each other rather than themselves, to avoid any last-minute changes of heart. Sitting in a circle, the first soldier would kill the man to the left of him, the next living soldier would kill the man to his left, and so on around the circle. When the circle of slaughter got back to the start, the process would repeat with the smaller group of people. Finally, the last man alive would fall on his sword. Josephus' problem was that he was much keener on living than dying - but he didn't want to let his fellow soldiers in on that secret. So, where should he position himself in the circle to be the last man standing?

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The math behind solving the Rubik's Cube

In this Scientific American video, Rubik's Cube master Ian Scheffler, author of the new book Cracking the Cube, explains some of the math behind "speedcubing." Scheduler's book sounds fascinating even though the only way I could get my Rubik's Cube solved is to hand it to my 10-year-old son's friend Luc who was the first to dazzle me with the fine art of speedcubery.

From the description of Cracking the Cube:

When Hungarian professor Ernő Rubik invented the Rubik’s Cube (or, rather, his Cube) in the 1970s out of wooden blocks, rubber bands, and paper clips, he didn’t even know if it could be solved, let alone that it would become the world’s most popular puzzle. Since its creation, the Cube has become many things to many people: one of the bestselling children’s toys of all time, a symbol of intellectual prowess, a frustrating puzzle with 43.2 quintillion possible permutations, and now a worldwide sporting phenomenon that is introducing the classic brainteaser to a new generation.

In Cracking the Cube, Ian Scheffler reveals that cubing isn’t just fun and games. Along with participating in speedcubing competitions—from the World Championship to local tournaments—and interviewing key figures from the Cube’s history, he journeys to Budapest to seek a meeting with the legendary and notoriously reclusive Rubik, who is still tinkering away with puzzles in his seventies.

Getting sucked into the competitive circuit himself, Scheffler becomes engrossed in solving Rubik’s Cube in under twenty seconds, the quasi-mystical barrier known as “sub-20,” which is to cubing what four minutes is to the mile: the difference between the best and everyone else.

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How a child math prodigy sees numbers as shapes

When 60 Minutes profiled child math whiz Jacob Barnett, he demonstrated how he imagined numbers as shapes. Numberphile's Simon Pampena analyzed Jacob's thought process. Read the rest

Mind-blowing explainer on fixed points

Understanding advanced mathematics can change how you see the world, so prepare for an eye-opening journey into the world of fixed points, courtesy of Michael at Vsauce. Read the rest

What’s heavier, a kilogram of steel or a kilogram of feathers?

The Scottish sketch comedy series Limmy’s Show! explores that classic riddle in the best way possible. As someone wrote on Tumblr, “This is me during every moment of math class.” Read the rest

Why swirling spheres shift rotation at a certain number

Swirling a ball in a cup gets it spinning in the direction of the swirl, but adding six more starts them swirling in the opposite direction.

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Fix your floppy pizza slice with Gaussian curvature

It turns out that folding a pizza slice lengthwise to improve its rigidity is a great example of the "Remarkable Theorem" by Gauss. Cliff Stoll explains. Read the rest

Let's teach programming as a tool for analyzing data to transform the world

Data-scientist Kevin H Wilson argues that computers are tools for manipulating data -- from companies' sales data to the input from games controllers -- but we teach computer programming as either a way to make cool stuff (like games) or as a gateway to "rigorous implementation details of complicated language," while we should be focusing on fusing computer and math curriciula to produce a new generation of people who understand how to use computers to plumb numbers to find deep, nuanced truths we can act upon. Read the rest

Remember Winnie Cooper from The Wonder Years?

Meet Danica McKellar who as an undergraduate in college co-published a paper titled "Percolation and Gibbs states multiplicity for ferromagnetic Ashkin-Teller models on Z2," research that resulted in the Chayes–McKellar–Winn theorem. Oh yeah, before that, McKellar was Winnie on The Wonder Years.

(And just to confirm, Josh Saviano who played Paul Pfeiffer did not grow up to become Marilyn Manson.)

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Photo of the raddest high school math teacher in 1970s SoCal

Math teacher at Dana Hills High School in southern California, late 1970s. Pitted. So pitted.

Posted by the engaged educator's son on r/OldSchoolCool and making the rounds again. Read the rest

Outliers: the statistical mysteries that hold the key to understanding

John Johnson and Mike Gluck's new book, Everydata: The Misinformation Hidden in the Little Data You Consume Every Day is a tour-de-force of statistical literacy. This excerpt, a chapter on understanding statistical outliers, is as clear an explanation of what an outlier is, and what it means, and why it matters, as you're likely to find.

Echo Observatory: beautiful, tactile fractal explorer with knobs on

Love Hulten writes, "The Echo Observatory is a handcrafted tribute to fractals and self-similar patterns. It's a mysterious artifact that both generates and visualizes complex mathematical formations, in real-time." Read the rest

Where does your birthday land on pi?

To celebrate Pi Day (3/14), have fun with MyPiDay, developed last year by Stephen Wolfram and company. Enter your birthday or any other number and see where it first appears in pi.

Background in Wolfram's post here. Read the rest

Vi Hart Pi Day rant 2016: best one yet

Fast-talking, doodling math genius Vi Hart (previously) really hates Pi Day, and every year, she celebrates her loathing with a fresh video pooping on your 3/14 parade. Read the rest

Proposal: replace Algebra II and Calculus with "Statistics for Citizenship"

Andrew Hacker, a professor of both mathematics and political science at Queens University has a new book out, The Math Myth: And Other STEM Delusions, which makes the case that the inclusion of algebra and calculus in high school curriculum discourages students from learning mathematics, and displaces much more practical mathematical instruction about statistical and risk literacy, which he calls "Statistics for Citizenship." Read the rest

Kickstarting a season of monthly Relatively Primes, a great math podcast

Samuel writes, "The mathematics podcast Relatively Prime (previously) is currently running a Kickstarter to fund a third season, this time with monthly episode. The episodes will features stories about how network theory can help better understand cancer, how a marijuana dispensary license lottery is designed, and the act of mathematical vandalism which liberated algebra from the shackles of arithmetic. There really aren't any other mathematics podcasts out there like Relatively Prime and if the Kickstarter is not funded there really won't be any at all." Read the rest

NSA and GCHQ's crappy Big Data techniques may be killing thousands of innocents

Researchers have taken a second look at the NSA SKYNET leaks, as well as the GCHQ data-mining problem book first published on Boing Boing, and concluded that the spy agencies have made elementary errors in their machine-learning techniques, which are used to identify candidates for remote assassination by drone. Read the rest

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