Posamentier A.S., Lehmann I. Pi: A Biography of the World's Most Mysterious Number

Prometheus Books, 2004. — 324 pages. — ISBN: 1591022002.It is the ratio of the circumference of a circle to its diameter, a transcendental number, and to some people, an obsession.
Posamentier (mathematics education, City College, CUNY) and Lehmann (mathematics, Humboldt U., Berlin) examine how pi has been an object of fascination from the Old Testament, through an act proposed in Indiana in 1897 setting its value, to a recent experiment with a supercomputer that netted a total of 1.24 trillion numbers to the right of the decimal point. Along the way they show how pi actually works according to Cusanus, Rumanujan, and even Wankel. The epilog contains pi expressed in 100,000 decimal places for the reader's enjoyment.