Exploring numbers:
Lots of interesting facts about numbers on BBC’s site, Exploring numbers, by Simon Singh. Some intesresting questions are:
Is it true that any map can be coloured with just 4 colours so that no two neighbouring countries have the same colour?
What is largest known prime?
How many shuffles are sufficient to achieve an acceptable degree of randomness in a deck of 52 cards?
I have read one or two other books by this author and they were great! He wrote a fantastic one on Fermat’s Last Theorem and I believe also one on pi, or was it encryption. Either way, the one I read was great!