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:

(x^4-\frac{1}{x^2})^5(x-\frac{1}{x})^6

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.