What makes a number weird, and why, as far as anyone can tell, aren’t weird numbers odd? What do monsters, moonshine, and 24-dimensional oranges have in common? Why couldn’t Sam Loyd get a patent for his famous fifteen puzzle? What is the significance of the statement "the smallest number not nameable in under ten words"? Can one infinity be larger than another? If you are fascinated by the weird, the odd, the curious, and the just plain puzzling, it’s no wonder that you’re drawn to mathematics. And, if you can’t resist the urge to indulge these fascinations–and discover plenty of new ones while you’re at it–welcome to The Universal Book of Mathematics.