This is the penultimate round of the hottest contest of the summer, The Big Internet Math-Off. We’re down to 4 competitors, each raring at the bit to show us more fun maths. In this first semi-final, we’re pitting Nira Chamberlain against Zoe Griffiths.

The rules are the same as always: take a look at both pitches, vote for the bit of maths that made you do the loudest “Aha!”, and if *you* know any more cool facts about either of the topics presented here, please write a comment below!