Here’s our annual round-up of what’s happening in sums/thinking at this year’s Manchester Science Festival. If you’re local, or will be in the area around 20th-30th October, here’s our picks of the finest number-based shows, talks and events.

# You're reading: Blackboard Bold

### Binary/Nail Varnish Puzzle – solution

Previously, we posted about Katie’s Binary Nail varnish tutorial video, and how you can use glitter (`1`

) and no glitter (`0`

) to encode binary messages in your nail varnish. We also posted an accompanying puzzle, stated as:

**Suppose I want to paint my nails on one hand differently every day for a month – so I need to use all 31 combinations involving glitter. Assuming that a nail painted with plain varnish can have glitter added, but a nail with glitter needs to be nail-varnish-removed before it can become a plain nail again, what order do I apply the different combinations so that you minimise the amount of nail varnish remover I’ll need to use?**

Here’s our take on the solution.

### Just how big is a big proof?

With news that a recent proof of the Boolean Pythagorean Triples Theorem is the ‘largest proof ever’, we collect and run-down some of the biggest, baddest, proofiest chunks of monster maths.

### The new Eurovision scoring system: the maths

It’s Eurovision time again! A chance for everyone to enjoy musical performances that are either good or so bad they’re good, ridiculous staging, and hilarious costumes, all sprinkled with a gently sarcastic Irish voiceover (if you’re lucky enough to be watching in the UK).

BUT WHAT’S THIS? They’ve changed the voting system? Don’t worry – some mathematicians are here to straighten it out for you.

### Katie’s Binary Nails Tutorial – and a puzzle

I’ve just posted my latest YouTube video, in which I explain how to use binary numbers to jazz up your nail varnish:

Alongside this video, I also have an associated puzzle for you to think about.

### Mind Games: 6 Nimmt!

*In this series of posts, Katie will be going on about some of her favourite board games and card games, and some of the interesting mathematics to be found there. If you’d like the chance to play a mathematical board game, why not find or start a Maths Arcade at university, or join your local MathsJam.*

6 Nimmt! (German: *Take 6!*) is a card-based game which involves a hand of numbered cards, each also containing a number of cow heads. The cards are played in rounds, and during each round everyone chooses a card to play, they’re played in order, and you may find yourself having to take cards. The aim of the game is to end with the fewest cow heads.

### EE = maths × sums²

Countdown number-nerd Lovely Rachel Riley has appeared in the latest advert for mobile phone agglomerate EE, alongside massive film node Kevin Bacon.

In the advert, Riley is unable to work out how anyone could not be enticed by the high mobile internet speeds (50% faster, apparently) offered by the company who are paying her to not be able to do so, and this is illustrated by a whole board full of equations and numbers which don’t seem to come to anything. Or do they?