(At last month’s big MathsJam conference, we asked a few people who gave particularly interesting talks if they’d like to write something for the site. A surprising number said yes. First to arrive in the submissions pile was this piece by Tom Button.)

The formula for the surface area of a sphere, $A=4\pi r^{2}$, is the derivative of the formula for the volume of a sphere: $V=\frac{4}{3}\pi r^{3}$.

This result does not hold for a cube with side length $a$ if the surface area and volume are written in terms of $a$. However, if the surface area and volume are written in terms of half the side length, $r=\frac{a}{2}$, you get the surface area $A=24 r^{2}$, which is the derivative of the volume, $V=8 r^{3}$.

### Robert Schneider, Mathematical Musician/Musical Mathematician

Robert Schneider is a rock star mathematician. I do not mean that in the metaphorical sense, as when it is applied, with a rather unmathematical lack of precision, to celebrity mathematicians such as Terry Tao, Cedric Villani, or Timothy Gowers. I mean it in the most literal sense: Robert Schneider is a mathematician and Robert Schneider is a rock star.

### Relatively Prime, All in a Name

“Prime. Prime? Prime! Prime factors, twin primes, pseudo-primes? No, no no. Relatively Prime? Yes, Relatively Prime.”

I have a problem, no matter how good an idea I have I can not start to work on it until I have a name. Some names are easy, Combination and Permutations was a name well before I ever had a show to use it, Science Sparring Society followed directly from the concept, and ACMEScience NEWS NOW actually told me what type of show I would be making. Other names are hard.

I had the underlying idea for Relatively Prime (get the first episode here) in an extreme bout of egotism and delusion of grandeur where I spent too long listening to Radio Lab, This American Life, and Snap Judgment and began to think, “Hey, I could do that, but for math.”

### The Mathematician’s Shirts

The shirt symbolizes the formality of a male-dominated society and of conformance to society’s rules. Mathematics, too, is a realm of formality and rules populated largely by men. Yet in both shirts and mathematics there is room for creativity and individuality.

In The Mathematician’s Shirt project, artist Madeleine Shepherd and mathematician Julia Collins set about challenging these notions by turning a collection of formal shirts (donated by mathematicians!) into mathematical art. Inspired by the work of mathematicians in Edinburgh, the fabric of the shirts got twisted into 4-dimensional shapes, woven into knots and stitched into different geometries.

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### How I Unofficially Broke The World Record That Never Was

One of the 70-digit subtraction sums I did for training purposes.

In April, a gentleman called B. Sai Kiran became, briefly, internet-famous for doing arithmetic. In Hyderabad, he subtracted a 70-digit number from another in the barest smidgen over a minute – 60.05 seconds, at the second attempt.