David Wells.
The Penguin Dictionary of Curious and Interesting Numbers.
Penguin. 1986
(read but not reviewed)
Why was the number of Hardy’s taxi significant?
Why does Graham’s number need its own notation?
How many grains of sand would fill the universe?
What is the connection between the Golden Ratio and sunflowers?
Why is 999 more than a distress call?
What is the largest known prime number?
All these questions and a host more are answered in this fascinating book. From minus one and its square root, via cyclic, weird, amicable, perfect, untouchable and lucky numbers, aliquot sequences, the Cattle problem, Pascal’s triangle and the Syracuse algorithm, music, magic and maps, pancakes, polyhedra and palindromes, to numbers so large that they boggle the imagination, all you ever wanted to know about numbers but didn’t know where to look is here. There is even a comprehensive index for those annoying occasions when you remember the name but can’t recall the number. Kaprekar numbers? Ah, yes, of course…