Anatole Beck 
Excursions into Mathematics [PDF ebook] 
The Millennium Edition

Since it was first published three decades ago, Excursions Into Mathematics has been one of the most popular mathematical books written for a general audience. Taking the reader for short "excursions" into several specific disciplines of mathematics, it makes mathematical concepts accessible to a wide audience. The Millennium Edition is updated with current research and new solutions to outstanding problems that have been discovered since the last edition was printed, such as the solution to the well-known "four-color problem." Excursions Into Mathematics: The Millennium Edition is an exciting revision of the original, much-loved classic. Everyone with an interest in mathematics should read this book.