# How to make: a hexaflexagon

#### You will need

• a long strip of paper a few cm wide, a printed template from here, or your own template from here.
• glue
• a protractor or set square

#### Instructions

1. Fold over the left end of the strip to make an angle of 120°.

# Top Ten vote: Colours of chalk

What is the best colour of chalk?

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# What’s hot and what’s not, Issue 03

Maths is a fickle world. Stay à la mode with our guide to the latest trends.

### HOT 5-minute talks

Show us your coolest stuff and let us chat to you later.

### NOT 40-minute conference snores

You lost everyone after that entire page of algebra, mate.

# Page 3 model: Traffic flow

Have you ever reached the start of a traffic jam fearing the worst—road works, an accident, a fallen tree—to later discover no clear reason for the delay? Then you fell victim to one of the strangest traffic phenomena: the phantom traffic jam. This ghostly foe may seem supernatural, but can actually be predicted through the theory of shockwaves.

# Dear Dirichlet, Issue 03

Moonlighting agony uncle Professor Dirichlet answers your personal problems. Want the Prof’s help? Send your problems to deardirichlet@chalkdustmagazine.com.

### Dear Dirichlet,

A new colleague at work is deaf, and I’m trying to learn BSL to communicate with her. I have commenced some classes at the local community college, but every time I converse with my hands, she cocks her head to the side.

Is this a social cue I’m missing?

— All thumbs, Royal Leamington Spa

# Prize crossnumber, Issue 03

Our original prize crossnumber is featured on pages 44 and 45 of Issue 03.

Clarification: In 39D, the integers should be positive and distinct.
Clarification: The answer to 40A is not 5362, as some websites claim. 5362 is the number of positions that could face you after 3 moves, not the number of ways to play 3 moves.

### Rules

• Although many of the clues have multiple answers, there is only one solution to the completed crossnumber. As usual, no numbers begin with 0. Use of Python, OEIS, Wikipedia, etc. is advised for some of the clues.
• One randomly selected correct answer will win a £100 Maths Gear goody bag. Three randomly selected runners up will win a Chalkdust t-shirt. The prizes have been provided by Maths Gear, a website that sells nerdy things worldwide, with free UK shiping. Find out more at mathsgear.co.uk
• To enter, submit the sum of the across clues via this form by 22 July 2016. Only one entry per person will be accepted. Winners will be notified by email and announced on our blog by 30 July 2016.

# Horoscope, Issue 03

Aries
Mar 21 – Apr 19

Today will be very odd for you, even though you are in your prime.
You share your sign with:
Sophie Germain
Torus
Apr 20 – May 20

A new mode of transport will give you a greater range. But do not be mean to those you love.
You share your sign with:
Carl Friedrich Gauss
Gemini
May 21 – Jun 20

A decision will have a great bearing on your future happiness. It will test your quick reflexes.
You share your sign with:
Blaise Pascal