This is a game played between a team of 3 people (Ann, Bob and Chris, say), and a TV game show host. The team enters the room, and the host places a hat on each of their heads. Each hat is either red or blue at random (the host tosses a coin for each team-member to decide which colour of hat to give them). The players can see each others' hats, but no-one can see their own hat.

Robin J Wilson's book is "not", as he assures the reader in the Preface, "a history of mathematics book in the conventional sense of the word". No indeed. It is, rather, a selective account of aspects of the history of mathematics which have appeared on postage stamps from across the world.

Money is peculiar stuff. It has no use of any kind apart from its value in exchange for something else, and this grows over time as it earns interest, or shrinks as inflation overtakes it. If you have money to invest, there are a bewildering array of different kinds of financial instrument available: interest-bearing accounts, bonds, pension funds, stocks and shares, options ...

Avid readers of popular books on the laws of nature are tolerably familiar with a number of facts. They know that electricity, magnetism and the weak force between elementary particles have been unified, that Einstein's theory of special relativity arose from an attempt to reconcile Newtonian mechanics with the laws of electromagmetism, and that his later theory of general relativity had something to do with the structure of spacetime.

The very fetching purple and yellow packaging states that this is "the" interactive geometry software. A little optimistic, perhaps; The Geometer's Sketchpad and Cabri both have their - not insubstantial - followings. And the previous release of Cinderella gave the impression of a terribly well-featured package lacking slickness. But therein lies the value of Version 1.2: slickness.

Similar triangles and colouring the plane