You have to be of a certain age to remember Johnny Ball, a kids TV presenter from the late '70s and '80s. He did popular education shows on... maths! Yep, kids TV did maths, without being dull. Amazing. I received this book some time in the earlyish '80s, and must admit I never read it properly.
My son's now inherited it and given it rather more attention than I did at the time. Re-reading it now, it's pretty awesome. There's a whole pile of dumb maths jokes, tricks, etc. For example, it teaches you how to know the day of the week any date falls on. It covers some real maths stuff, too. For example, it covers the platonic solids - complete with how to construct pop-up versions, find all the possible nets to make them etc. It mentions simple versions of the Brouwer fixed point theorem in passing. That kind of thing. It's surprisngly good, and I'm sad I never appreciated it at the time.
But then I'm glad my son's reading it. :)