I almost wrote "I won't dignify that question with an answer", but I reconsidered since 100 things is a minute sample. It's by the mathematician John D. Barrow, and it covers a wide range of topics, nearly every one is unrelated to any other, except that their explanations or interesting highlights are all mathematical in nature. Also, each of the 100 chapters is headed by a fantastic and sometimes barely relevant quote.
The title isn't entirely accurate. I knew all about the first one. But that's it. ("Why pylons are made of triangles", but it also explained some fascinating properties of polyhedrals).
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