# Weekend at MathsJam

Chalkdust visits popular maths’ biggest conference

Matt Parker, James Grime and Matthew Scroggs

@stumpyface meets @matheknitician’s Menger sponge.

Fifty 5-minute talks, two days, far too much cake to vote on, and half a dozen people trying to show you the ring-on-a-chain-trick (but more on that one later). These are just a few of the highlights of our weekend at the MathsJam Conference.

The conference is now in its sixth year, and brings together maths enthusiasts from across Europe. This year 159 people showed up to share anything they thought was cool in the celebrated lightning talks, table sessions, or over an excellent Sunday roast. Interesting facts we learnt included:

James Grime, Matt Parker and Matthew Scroggs enjoying Chalkdust.

• Traffic jam shockwaves travel backwards at 12mph,
• You can create a magic square from the decimal expansion of 1/19,
• You can measure the area of a scrap of paper with a bicycle.

The first rule of MathsJam is to let you work stuff out for yourself. In this spirit, here are some things for you to try:

• What do you spot in the decimal expansions of 100/9899 and 10100/970299?
• If you flip a coin, is THT or THH more likely to come up first?

After a day full of talks, the evening was filled with games and workshops. The game du jour was Dobble, a spot-the-matching-symbol game which only got mildly violent. Being MathsJam, someone noticed that the symbols could equally validly be replaced by further Dobble cards, producing a Dobbleception loop that was amazing but totally impossible.

### Mathematical cake competition

One of the highlights of the weekend was the mathematical cake competition. Which of these delicious mathematical desserts would you have voted for?

Which cake is the best?

View Results

### The ring-and-chain trick

It would be near impossible to get through a MathsJam weekend without seeing the ring-and-chain trick: Imagine dangling a closed chain up through a metal ring then letting go of the ring. What do you think will happens? Once you’ve thought about it, watch this:

We had a great time at MathsJam: the atmosphere was welcoming, everyone was friendly, and the organisation was superb. We’ll see you there next year with Issue 4.

MathsJam conference is organised by Colin the Juggler. Details for MathsJam Conference 2016 will appear in the new year. In the meantime, the next monthly MathsJam is next Tuesday.

Adam is an assistant professor at Durham University, where he investigates weird, non-Newtonian fluids. If he’s not talking about the maths of chocolate fountains he is probably thinking about fonts, helping Professor Dirichlet answer your personal problems, and/or listening to BBC Radio 2.

Huda Ramli is a PhD student at UCL, working on stochastic models of atmospheric dispersion.

Matt is a PhD student at UCL, working in the fields of general relativity and cosmology.

Matthew is a postdoctoral researcher at University College London. He hasn’t had time to play Klax since the noughties, but he’s pretty sure that Coke is it!

• ### Crossnumber winners, Issue 17

Did you solve it?
• ### On the cover: VisualPDE.com

Ben Walker, Adam Townsend & Andrew Krause invite you to play with their fun online PDE visualiser
• ### Crossnumber winners, Issue 16

Did you solve it?
• ### Prize crossnumber, Issue 16

Can you solve it?
• ### Cryptic crossword, Issue 16

Can you solve it?
• ### Crossnumber winners, Issue 15

Did you solve it?