### 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.

### Are you sure 51 isn’t prime? – Analysing the results of the “Is this prime?” game

Two months ago, I bought isthisprime.com and not only set up the internet’s fanciest primality-checking service, but also invented a rather addictive game.

It quite quickly went viral, or as relatively viral as a maths game can get, with people tweeting their high scores and posting the link to reddit and Hacker News. I realised fairly soon that I should put in some stats tracking, to see if there were any interesting patterns in the data (and also to inflate my ego as the “games played” counter went up). I missed the first big spike in traffic, but on the 9th of March I wrote a script which saved a record of each game to a database.

The mad rush settled down quite quickly but there were still occasional spikes as different sites or people with lots of twitter followers found the game. Now, after two months, I’ve got data for just under 350,000 games. That’s a decent amount of information!

### Carnival of Mathematics #131

Welcome to the 131st edition of the Carnival of Mathematics, a monthly blogging carnival which scoots its way round the internet, rounding up maths-related blog posts from the month of January.

### Open Season: Pancake Flipping

In this series of articles, I’m writing about mathematical questions we don’t know the answer to – which haven’t yet been proven or disproven. This edition is a topical one, for Pancake Day (Shrove Tuesday, celebrated in the UK this year on 9th February).

Some of the best mathematical teasers are those which originate in a real-world problem – although the problem for pure mathematicians is that that happens much less often than it does for applied mathematicians, who are presented with interesting real-world problems all the time. That’s why it’s especially nice when a more pure one pops up, and that’s exactly what happened to mathematician Jacob E Goodman, back in 1975.

### Books a 14-year-old who’s good at maths might enjoy

My good friend David Cushing popped on Facebook messenger to ask me a question:

I did tweet it, and I got a lot of good responses. Before I tell you about those, I’ll quickly list the books we mentioned above, that of course a keen 13-year-old already has.

### The Aperiodical’s Actually Hexagonal Snowflake Competition 2015

COMPETITION DEADLINE EXTENDED – SEE BELOW!

To celebrate the year end, as well as our daily Advent Calendar posts, we’re also running a little competition – last year we did a pun competition, and this year it’s something a bit more crafty – well, it’s a knitting competition in which the knitting is optional.