A few weeks ago we posted the puzzle on the right – well, here’s the answer.

A simple pendulum has a period given by

If you insert that into the expression in the puzzle you get

That simplifies to πg – which you could otherwise write as pi g!

Not too complicated, providing you spot the trick! If you think of or find similar puzzles, why not let us know through Twitter, Facebook, email or our contact form.

This puzzle was originally posted in a quiz by I G Mansfield at edrith.co.uk – you might even like some of the other quizzes and games available there!