One to Nine
Amongst the topics are Sudoku (including the killer variety), number theory and the nature of musical scales - why are there 12 notes in the octave rather than say 19. There's a look at various topics in physics - theories of everything, which Hodges suggests would be better named monolithic theories. There's also plenty about computers and what they can and can't do.
Hodges has clearly tried to make this book accessible to non-mathematicians. At the start there are few equations, but the style did seem to be a bit 'poetical' to me, which I found offputting. Later on the style settled down a bit, but more equations began to appear. I did feel that having introduced such a variety of new topics, Hodges should have given the readers more resources to follow up those which interest them. The are some notes on Hodges website www.cryptographic.co.uk, but I would hope that more will appear.
One thing that Hodges feels strongly about is that mathematics shouldn't be 'force fed', and this point of view is reflected in the book. If you agree with that viewpoint then you might like to give this book a try.