Here’s a game I’ve been trying to make for a while.

For a while I’ve had a hunch that there’s fun to be had in moving between numbers by using something related to the prime numbers.

Over the years I’ve tried out a few different ideas, but none of them ever worked out – they were either too easy, too hard, or just not interesting. This time, I think I’ve found something close enough to the sweet spot that I’m happy to publish it.

Prime Run is a game about adding and subtracting prime numbers. You start at a random number, with a random target. Your goal is to reach the target, by adding or removing any prime factor of your current number.

Every now and then a phrase pops into my head and won’t leave until I write it down or tell it to someone else.

One day the little voice in my head suggested putting “Didn’t” before the classic series of maths textbooks, Graduate Texts in Mathematics.

So I found a cover of a GTIM book, stuck “Didn’t” on the front and changed the title to an in-joke about not understanding category theory, and was happy with my life.

But then I thought that it would make sense to make a whole series of these, so I spent a couple of hours making a meme generator.

A while ago I made myself a calculator. I don’t know if anyone else uses it, but for the particular way I like doing calculations, it’s been really good. You’d think that if a calculator does anything, it should perform calculations correctly. But all calculators get things wrong sometimes! This is the story of how I made my calculator a bit more correct, using constructive real arithmetic.

One thing you need to think about when making a calculator is precision. How precise do the answers need to be? Is it OK to do rounding? If you do round, then it’s possible that errors accumulate as you compose operations.

I’ve always wanted to make a calculator that gives exactly correct answers. This isn’t strictly possible: there are more real numbers than a finite number of bits of memory can represent, or a digital display can show, no matter how you encode them. But I’m not going to use every real number, so I’ll be happy with just being correct on the numbers I’m likely to encounter.

At the 2021 UK MathsJam Gathering, I gave a talk on a subject that has bothered me more than is reasonable: the graph-theoretic layout of the narrative of the baby’s book Each Peach Pear Plum, by Janet and Allan Ahlberg.

It’s one of my son’s favourite books to fall asleep to. It was his older sister’s favourite, and mine and my wife’s when we were little. I agree with the quote on the back cover, that it’s “the perfect first book”.

Here’s a roundup of mathematical things that have happened in February 2022.

Ukraine

The deeply troubling and developing situation in Ukraine has implications for the 2022 International Congress of Mathematicians (ICM) due to take place in St. Petersburg, Russia in July. A group of Ukrainian mathematicians has issued a call for mathematicians to boycott the event. National organisations around the world have been issuing statements setting out their positions, standing down their participation and calling on the International Mathematical Union to not hold the event as planned. Here are some we spotted:

The International Mathematical Union (IMU) itself wrote to its member organisations expressing its deep concern, acknowledging the calls and saying it is assessing the situation.

Other news

The organisers of the Gathering 4 Gardner recreational maths conference have announced that this year’s event, taking place in April, will be a hybrid event with 50% discount for online-only places, making them a snip at $200. Registration is restricted to previous attendees and invitees, but it is possible to nominate yourself or someone else for an invitation.

Casualties of the recent storms in the UK apparently also include Newton’s apple tree – not the actual tree an apple fell on his head from, but scions of the original are planted all over the UK and one of the ones at Cambridge, which was planted in 1954, hasn’t survived the combined effects of Storm Eunice and gravity. More info in this excellent Twitter thread.

The Royal Statistical Society has released a report entitled Behind the numbers: The RSS puts the statistical skills of MPs to the test, in which they report the results of asking an anonymous unspecified group of Labour and Conservative MPs a series of simple stats and probability questions. The survey concluded that while MPs performed better than they did in a similar test ten years ago, their stats skills were still sub-par. It may not be as unambiguous as the research seems to claim though – Rob Eastaway has thoughts about the questions used.

The winners of the 2022 Mathical book prize, an annual award for fiction and nonfiction books that inspire children of all ages to see maths in the world around them, have been announced. The winners look to include some lovely titles, including Maryam’s Magic – the story of mathematician Maryam Mirzakhani – and the fantastic-sounding Uma Wimple Charts Her House. (via Jordan Ellenberg)