Next meeting: Tuesday, 24 March

The next Portsmouth MathsJam meeting is on Tuesday, 24 March, from 7.30 p.m. in the King Street Tavern, Southsea.

Please join us for maths-themed puzzles, games and conversation.

Feel free to bring along anything maths-related that you find interesting.

MathsJam meeting 17 February 2015

The latest Portsmouth MathsJam meeting was attended by 11 people, which we think is a record number, and included two new and very welcome attendees, Ruth and James.

Jack1 (there were two Jacks attending) had brought along some coin sliding puzzles which were designed by Bob Hearn and originally appeared on the website way back in December 2005. They can be found on this page (scroll down to the entries for 04 December). We decided these were much trickier than they looked, but Ruth persevered and found a perfect solution for the 66 move puzzle.

Meanwhile, several MathsJammers were attempting some other physical puzzles including the Bedlam Cube, which James managed to solve, and Rubik’s 360 which, sadly, was beyond anyone that attempted it. (The Bedlam Cube is quite a well known puzzle and once appeared on Dragons’ Den: YouTube link.)

As usual, the MathsJam Twitter feed had some interesting puzzles including a point in a square problem from Alison Kiddle, and a cow tethered in a circular field problem. I subsequently found this latter question, with solution, on math.stackexchange.

Finally, we settled down to an old favourite: Perudo. We played mostly in pairs and after a close contest Judy/Gabor edged out Jack1/Nick (a.k.a. PerudoJedi), with Andy a close third.

Overall, this was definitely one of our busiest and most enjoyable MathsJam meetings.


Next meeting: Tuesday, 17 February

The next Portsmouth MathsJam is on Tuesday, 17 February, from 7.30 p.m. in the King Street Tavern, Southsea.

Last month we played some games of Set, attempted several geometry problems like this one, discussed the 2015 game, and explored graph theory (that’s what I’m calling it anyway) in the Android puzzle game RGB Express.

As always, feel free to bring along anything maths-related that you find interesting.

Advent puzzles on Twitter

To tide us over until the December MathsJam meeting (and then beyond), I’ll be posting some Advent maths puzzles to our Twitter feed.

There’s four puzzles with a similar theme today and these will be followed by a puzzle a day until Christmas Eve.

You can follow us on Twitter @MathsJamPOR, or use the Follow button in the Twitter feed to the right.

MathsJam meeting 18 November 2014

One of the great things about MathsJam is that you can bring along anything even remotely maths connected for people to try. Games, puzzles, quizzes and general maths problems are all regularly brought along. Here are some of the things I tried at the latest meeting.

Jack produced another Only Connect-style maths quiz and much time was spent pondering the answers to the clues.

Jack also had some algebra questions. Lots of algebra questions! I particularly liked this one:


Show that the coefficient of the x^{-12} term of the above expression is -15.

The MathsJam Twitter feed contained several interesting questions:

  • What is the sum of the digits of the sum of the digits of the sum of the digits of 2014^{2014}? It was claimed that this could be solved with “only primary-school maths facts”, although we couldn’t find an easy solution ourselves.
  • Show that 1 and 9 are the only square numbers composed entirely of odd digits. We did manage an acceptable proof of this.
  • What is the shortest line that bisects an equilateral triangle? The line need not be straight.


Twitter feed and site update

I’ve made some updates to this site.

The main change is the addition of a Twitter feed for MathsJam Portsmouth. You should be able to see our most recent posts in the right-hand sidebar. Please follow us @MathsJamPOR.

The other change is that I’ve managed to recover three older posts on this blog which had somehow got misplaced, and have restored them to their rightful place in our blog timeline.

MathsJam meeting 21 October 2014

The regular monthly meeting of Portsmouth MathsJam was held, as usual, at the King Street Tavern in Southsea. There was a welcome return for Andy, who has recently moved back to the region, and there were eight MathsJammers in total.

Most of the evening was spent trying various puzzles from a collection called Brain Busters that Jack had brought along. The puzzles were created by Ed Pegg Jr and you can find a pdf of them all at

(We very much recommend Ed Pegg Jr’s site It has a huge collection of maths-related puzzles and links.)

Our own Edd posed this puzzle: consider two triangles with side lengths 5, 5, 6 and 5, 5, 8 respectively. What is the ratio of their areas? Before you go digging up your old book of trigonometric formulas, there is a simple way to find the solution.

Finally, we also enjoyed seeing the photos of other MathsJammers constructing cubes for the MegaMenger project. See for more information, or search @megamenger or #megamenger on Twitter for many pictures.