It gives me huge pleasure to announce that the winner of the Big Internet Math-Off 2019, and consequently the World’s Most Interesting Mathematician (2019, of the 16 people I asked, who were available in July and agreed to take part), is:

**Sophie Carr!**

The final was incredibly closely fought, with the lead changing several times over the course of the day. In the end, Sophie’s pitch about Bayes’ theorem and pregnancy tests just pipped Sam’s pitch about grids, with 53% of the votes cast.

I asked Sophie to sum up her Math-Off journey. Here’s what she said:

It took five people to persuade me to enter the competition and that my maths was good enough to compete. The only way I could think to enter was to talk about the maths I’ve enjoyed so much that I wanted others who might not have heard about the topic before to get lots of the fun “ooh” bits in one go. It also meant I was fairly sure I knew enough about the maths to limit the mistakes I’d make and that I could cover applied maths and statistics (from my A levels through all of university). Writing the pitches was tricky, yes from a time perspective, but I wasn’t the only one in that situation so I also stopped worrying that anyone reading the articles wouldn’t think that I’d done my best. This was helped by the fact that absolutely everyone in the competition has been friendly and welcoming, the organisers and competitors have made the whole experience enjoyable.

Given I wasn’t sure I should even enter the competition, winning the competition was never on my mind. As far as I was concerned becoming a sticker in a proper sticker book (stickers coming in packs of 5 with shiny stickers) was the highest accolade possible. Literally up there with famous footballers, the sticker book was one of the highlights of this year. I’ve told everyone that I’m a sticker in a sticker book! It was only when I won the group stage that I suddenly realised I had to find a semi-final pitch. Never, ever did I think I’d win that round so I hadn’t given a second thought to what I would write about in the final. I am thrilled that what Sam and I wrote for our final pitches were so closely enjoyed by those who voted. The UK/US time difference added a real element of suspense and the “graph-fairy” did a great job of tracking the difference in votes. When I woke up and Sam was 108 votes in the lead, I did think he’d won. However, there were two and a half hours left so it was still “game on”. Watching the difference close down was surreal – and with an hour to go there was only 5 votes in it – was equally nerve-wracking and thrilling. I couldn’t actually believe it when I went into the lead. Winning the “Math-Off” hasn’t really sunk in yet, I’ve got the same title as Dr Nira Chamberlain, and that’s not something I ever thought I’d say! I’m also in awe of the others who pitched so I’d say that the real winner is the fact we’ve managed between us to create 54 posts of fun maths that can be viewed and engaged with by anyone. That’s an awesome legacy.

Congratulations, Sophie!

Nobody has yet corrected me on the number of competitors.

Thanks also to Katie Steckles and Matthew Scroggs for helping out with the running of the competition. Katie did some scurrying behind the scenes to keep the posts in order, and Scroggs took it upon himself to make an unofficial sticker book, which I wasn’t expecting but have enjoyed hugely.

I’ve also asked the other competitors to sum up their own experiences:

**Anna Haensch:** I became acquainted with many new math enthusiasts as a consequence of this Math-Off, and my Twitter feed is the better for it. In addition, I was surprised to learn that my own brother is a huge fan of ultimate tic-tac-toe and I would never have known had I not shared my posts with him, thereby changing all future holiday gatherings for my family. Overall, I have to say that it warms my heard that you 3, plus 16 contestants, plus 50,000 readers are all so driven by the fun of sharing math (sometimes it’s easy to forget the fun parts). Also, apologies again for that nail-bitingly late entry in the last round!

**Jorge Nuno Silva:** The Big Internet Math-Off is a tough competition in which many – math lovers and other sophisticated people – win!

**Jim Propp:** It was fun but time-consuming. I’ll reap the benefits in the Fall, when I get to finish already-half-written essays for my Mathematical Enchantments blog, instead of having to write them from scratch, at least for the next few months. I was repeatedly struck by how bad I am at predicting whose pitch will win. I believe the underlying directed graph containing an edge from $x$ to $y$ iff pitch $x$ would beat pitch $y$ if the two of them were pitted against each other is highly nontransitive, and may even have many of the features of a random graph.

**Sam Shah:** It was super fun trying to put things in writing that tried to take the reader on a journey mimicking my own sense of bafflement, wonderment, and curiosity. In fact, that’s what I try (and often fail) to do as a teacher with my students. But honestly, more fun than that was seeing how everyone else did the same with math topics they love, each with their own style and personality.

**Colin Beveridge:** While I’m proud of my contributions, the voting patterns meant my biggest Math-Off highlight was people begging for my legs in the stickerbook. And I still think the Messi joke deserved another 30 votes.

**Lucy Rycroft-Smith:** I particularly enjoyed my opportunity to take part in the Math Off this year because it gave me an impetus to crystallise some thinking I’d been doing for some time. When we write about maths, who is our audience and what is our concomitant duty to them? Who ‘gets to’ (makes less than free choices to?) read about maths and who doesn’t, and why does that happen? Consequently, my first few pitches were an experiment in explaining simple ideas in different styles. My last pitch was the real experiment through- what would happen if I went completely meta and wrote about the Math Off in the Math Off? (The rest is left as an exercise to the reader) Thanks for having me; it’s been a real pleasure, and such a joy to read some of the wonderful and passionate pitches on display. Some wonderful spin-off collaborations have already been planned, and I hope more will come in the future. Particular thanks to Christian and Stecks for seamless running and promotion, and to Scroggs for such a great idea with the stickerbook- it was a lot of fun.

**Alaric Stephen:** Math Off has given me daily conversations with my students about deep and surprising topics. Clearly a lot of effort went into a lot of the pitches and I’m very grateful to all involved. I also can’t really remember how I started my day before the morning sticker pack opening.

**Vicky Neale:** The best thing for me about the Big Math Off has been making new maths friends, closely followed by learning about exciting maths from others, and being prompted to get on and do some maths knitting projects I’ve had in mind for ages. I found it hard to tell how much we were reaching out to new people and how much we were talking to each other. Of course, talking to each other is great, but we all put lots of thought into our pitches, and some of them would have been ideal for reaching beyond people who already know they want to spend July thinking about exciting maths.

**Grant Sanderson:** As someone who usually makes videos, which can be pretty long at that, I found this a wonderful excuse to think up topics which could be interesting in the pure writing. And reading everyone else submissions was a delight. As far as criticism goes, the only piece of feedback I can think of is that I found it a bit confusing whether or not we were aiming to explain things. On the one hand, to get an “aha” moment requires a satisfying explanation, but on the other hand, it sounds like the aim was to keep things shorter and more informal. Then again, perhaps that’s not a criticism of the math off, but of math communication in general :)

**Rachel Thomas:** It’s been a great opportunity to hear so many brilliant maths stories, and find some really interesting maths people. And it’s so exciting to see so many people getting involved. And we were very excited by the unexpected bonus of being in a sticker book!

Last year in my summing-up post I listed some of my favourite pitches. I’m not going to do that this year, mainly because I’m too tired, but also because there are too many to choose from. We had 54 pitches this year. That’s enough maths to fill a book! Go back and read the lot of them again.

I’ll finish with a couple of stats: the pitches were collectively read by over 50,000 people, and 5,776 votes were cast. And ZERO EXTREMELY FAIR TIEBREAKERS USED! Woohoo!

Let’s do it again next year!