Matt Parker is a nerd, and proud of it. So nerdy that, in a list of the nerdiest things he’s ever done, hiking for three days through the Australian outback to document a ‘confluence point’—an integer intersection of a line of latitude and a line of longitude— “might not even make the top ten”. A quick scroll through his YouTube channel (standupmaths) shows videos with titles like *Back to the fax machine*, *Speed Rubik’s cubing for drunk people* and *Stand-up comedy about equations that correspond to vortex motion*. In the latter, he makes jokes about integration and pokes fun at physicists for calling a torus a doughnut. The video also has over 300,000 views, so clearly there is a huge audience for his brand of nerdiness. When we met Matt, on a grey evening in late January, he was about to embark on a week of talks around the country where he would share his enthusiasm for maths at festivals and in schools. “I want people to learn stuff, sure, but I’m also trying to do a bit of maths PR. I want to make the nerdy kids cool for the day.”

## An unexpected journey

Although Matt has a clear mission now, he admits this wasn’t always the case. “Basically, I didn’t have a career plan. I’d done a bit of tutoring at university and loved that, so I got my teaching qualification and moved to the UK.” He had always been interested in making videos and writing comedy, and while working as a teacher he realised he was missing that creative outlet. So, the stand-up mathematician was born. At first, his comedy routine played off the fact that he was a mathematician “who expects life to be logical.” Being a teacher also helped: “When you say you’re a maths teacher then, for better or for worse, people have an image of that. And you can play with it.” Gradually the comedy became nerdier, he started being more involved with university engagement programmes, and eventually in 2012 he left teaching and made the transition to being a full-time outreach mathematician.

These days, Matt gives talks to nerds and non-nerds alike. “If I can make a room full of nerds laugh at a joke about spreadsheets, that’s great. But in some sense, that’s the audience.” Working with kids, on the other hand, is much more challenging and requires careful judgement. “The moment they think you’re trying to impress them, it’s all over.” You have to pick your jokes wisely, and make sure that the educational content still comes through. If it works though, and you can get teenagers who don’t want to be there accidentally enjoying themselves while they learn about mathematics, then it’s a “much bigger achievement.”

It is really important for maths outreach people to keep in touch with teachers…to check what we’re doing is useful.

It’s clear that Matt’s time in teaching has had an effect on the work he does today. His goal is to keep his sessions relevant to what teachers are doing at school, and make them a part of the experience, which “keeps the excitement going” once the day is over. “I don’t want to do shock and awe mathematics, where they go back to the classroom and say, why aren’t our lessons like that guy’s?” This is also the reason that he started MathsJam, the monthly meet-up series that brings together mathematicians of all stripes in pubs around the world. “It is really important for maths outreach people to keep in touch with teachers, to find out what they need and whether what we’re doing is useful.” It’s a great approach to outreach: something that fits within the system and complements the everyday job of educators, rather than creating a division between ‘fun maths’ and ‘school maths’.

## Video made the mathematician

In recent years, a lot of Matt’s most well-known output has been through YouTube videos, either from his own account or as a guest on the mathematics channel Numberphile. Here again we find him carefully balancing his different audiences. “I would be disappointed if my videos were only watched by maths people, but likewise I would be disappointed if I don’t occasionally put out videos for that demographic.” Sometimes Matt can tell that a topic is going to provoke interest among non-mathematicians. One example of this is a video with Hannah Fry titled *The mathematics of winning Monopoly*, where they crunch the numbers to work out which squares are worth buying. At other times, the internet doesn’t react the way you would expect and a video that took a lot of effort to produce barely makes a splash.

So some videos land well and others don’t, but being mathematicians we felt the best way to understand Matt’s career as a YouTuber was to take an average. Specifically, to watch his median video, according to quality. “I made a video once about ordinal and cardinal numbers. And it was fine. Just, fine.” Cardinal numbers are used to count how many of something there are (you can have zero apples, one orange, three pineapples, etc) and ordinal numbers *order* items into first, second, third. Matt wanted the video finished in time so that he could show it at a talk, where he would test his audience’s powers of self-organisation. Everybody who came to the talk was given a slip of paper with a number written on, and the challenge was for them to comment on the video online in the correct order. “It got to over a hundred, before I released the video to the public and they broke it.”

Over the course of more than one hundred videos, Matt’s YouTube channel has covered all sorts of mathematical and mathematically-related topics in an entertaining, accessible way. But there are some topics that he won’t ever make a video on. The Riemann hypothesis is a classic example of a popular, famous topic that he feels just won’t work on YouTube. “First of all, you’re going to have to do plotting a complex function… and the Basel problem, and what the zeta function is generalising. Suddenly you realise there’s so much background stuff, that a video is just not the right format.” This desire to tell a story all the way through is what led to Matt’s first book: *Things to Make and Do in the Fourth Dimension*, which was published in 2014. Although the book deals with lots of different mathematical topics, ranging from knots to different size infinities, Matt was “setting up everything he needed to do the Riemann hypothesis *properly*.”

## Making mistakes

Matt’s new book, released in March 2019, is called *Humble Pi*. The book is framed as a collection of errors in mathematics: times when people made a mistake and faced real-world consequences. But actually, Matt says, the real aim was to show people how maths is “incredibly useful and underpins society.” By telling stories and anecdotes about these mistakes, he hopes to reach people who “wouldn’t normally pick up a maths book” and show them that maths is everywhere… just you might only notice it when it goes wrong.

The stories contained in the book range from the serious to the sublime. For example, in 1997 the cruiser *USS Yorktown* was left powerless during training manoeuvres after a crew member tried to divide by zero and crashed all the computer systems that controlled the engines. Another chapter tells of a flight in Canada that had to make an emergency landing after ground crew twice used the wrong amount of fuel. Their mistake? To calculate the amount needed in kilograms, and then load the tank with that many pounds. But Matt was cautious not to fill the book with disaster tales. “Nobody dies in any of the [aviation] stories. It’s safe to read if you’re scared of flying.” Some of them—like the tale of Steve Null, whose unfortunate name was incompatible with the company database—are just there to tickle you.

And yes, the book does include a mistake that Matt himself has made. The ‘Parker square‘ is an attempt at making a 3-by-3 magic square using only square numbers. He suspected that his methods weren’t perfect, but he thought it would be fun so he gave it a go. And, lo and behold, his answer included a mistake (check the diagonal sums in the image on the right). Matt uses the Parker square to teach us another important lesson: mathematics is often about making mistakes. “Mathematicians are not people who find maths easy, they’re people who enjoy that it’s difficult… we make mistakes all the time. People wear T-shirts that confirm this.”

Another part of Matt’s life these days is that he regularly signs calculators. What began as a light-hearted joke now sees hundreds of school children around the country with their names Sharpie-d in the encoding standard Ascii on their devices. Matt takes great pleasure in doing this; not only is it an ironic celebration of nerdiness, and gives the students some maths to do if they want to read his message, it serves as a reminder of their experience that will last for months or years afterwards. “If they get so involved that they want to get their calculators signed, then I think that’s hilarious.”

As a mathematician and comedian, Matt seems to be in the middle of two very different worlds. But he’s happy there, describing it as a “stable equilibrium”. He has many outlets for his creative side, and says that he could “probably find something else to scratch that itch if he wasn’t doing comedy.” But as for maths, there’s nothing that can replace it. “It’s much more pervasive in your life. It’s something that you’re always thinking about.” Even when you make mistakes, “it’s worth putting the effort in, because when you get it right it’s just so useful. And so fun.”

*Would you like to win a signed copy of *Humble Pi*? Tell us about a time when you’ve made a mistake in mathematics by sending us an email before 9 September 2019, and Matt will pick a winner!*