Maths Olympiad, Part 3

I received my Certificate of Distinction a few days ago, so I'm pleased.

I also got an IMOK (Intermediate Maths Olympiad and Kangaroo) keyring and a little booklet with the papers and answers in it.

The keyring has a puzzle on the back which is really hard and I haven't solved yet. I say puzzle, it's just a maths question really.

RJ