Maths Gear

I help with a team called Maths Gear. It was started by my good friends Matt Parker and Steve Mould. We all do maths shows, and when we wanted a prop to show something cool we would look to see if it was available to buy but we were often disappointed. But, we figured, there must be lots of other people out there who would like to buy these things too, so we set up Maths Gear.

Below are some of the products Maths Gear sells that I had a hand in designing. But there are many other things to buy so you should check out the whole site.

We are the only website to have their products peer reviewed.

Grime Dice


Non-transitive dice are amazing. You and your opponent each pick a die and roll, whoever has the highest number wins. A set of three non-transitive dice work such that, on average, the first die beats the second, the second die beats the third, and the third die beats the first. This means that, if your opponent picks first, you can always pick a die with a better chance of winning. Pretty sneaky!

The idea isn’t new and goes back to the late 1960s. I was challenged to design a set of five non-transitive dice. That itself is not so hard. So I decided to make a set that also included a lot of other cool properties. This set then allows you to play a three-player game and beat two opponents at the same time! I admit I was thrilled when people started to refer to them as Grime Dice.

We now make Grime Dice to buy. Either the set of five, a set of three, or sets for schools, which come with a lesson plan.

If you want to find out more about the maths, here is a detailed article I wrote about the dice.

Amicable Hearts

amicable hearts

I’m often asked what is my favourite number – and then I disappoint people by saying I don’t have one. (Really, would you ask an author what his favourite letter is?) But I do have a favourite story about numbers.

If you take the numbers that divide 220 (the factors of 220, not including itself) and add them together you get 284. If you take the numbers that divide 284 and do the same you get 220. They come as a pair. This is the smallest such pair and are called amicable numbers, and in ancient times these numbers represented mutual friendship, perfect harmony, and love.

In medieval times they would write 220 and 284 on talismans, one for you to wear and one for you beloved. Here we present our modern equivalent, amicable number keyrings. One for you and the other for the one you love, such that the two halves fit together.

I’m just a big softy really.

The Utilities Problem Mug

utilities mug

The Utilities Problem is one of my favourite puzzles.

You have three houses, and three utility companies – the gas company, the water company, and the electric company. Each utility must be connect to each of the three houses, which you draw on the picture with a line. Can you connect each utility to the houses – without crossing the lines?

Even if you have tried this puzzle before, have you ever tried it on a mug? It is not the same.