Cosmos by Carl Sagan. (1980, ISBN 0-394-50294-9) Based on the the 13-part TV series of the same name. That TV series was recently updated with a newer version with Neil deGrasse Tyson. A great book. Contains a lot of interesting stuff, a bit out of date in terms of space exploration (a lot has happened since it was written in 1980.) Still worth reading ( you can find used copies very cheap on Amazon.) I got my copy back in the 1980s.
Contains a proof that the square root of 2 is irrational. Discusses the Googol and the Googolplex. This book contains much information about science and the history of the world, etc.