Exercise for the reader
More from Chalkdust

The Spirit of Mathematics
We review the ninth of this year's nominees for Book of the Year
On the cover: Some assembly required
Trippy brain massages from Sam Palmer's artwork on the front of Issue 16
On the cover: Euclidean Egg III
Euclidean Egg III makes the cover of issue 06!
The analytics of healthcare
Simple Statistics can help businesses make informed decisions
What’s your favourite function? Part II
We have received loads of feedback from people telling us their favourite function
Newsletter puzzles
These puzzles appeared in the Chalkdust newsletters. You can find the answers here and sign up for the newsletter here.
