Number theory, the Queen of Mathematics, is an almost purely theoretical science. Yet it can be the source of endlessly intriguing puzzle problems, as this remarkable book demonstrates. This is the first book to deal exclusively with the recreational aspects of the subject and it is certain to be a delightful surprise to all devotees of the mathematical puzzle, from the rawest beginner to the most practiced expert. Almost every aspect of the theory of numbers that could conceivably be of interest to the layman is dealt with, all from the recreational point of view. Readers will become acquainted with divisors, perfect numbers, the ingenious invention of congruences by Gauss, scales of notation, endless decimals, Pythagorean triangles (there is a list of the first 100 with consecutive legs; the 100th has a leg of 77 digits), oddities about squares, methods of factoring, mysteries of prime numbers, Gauss's Golden Theorem, polygonal and pyramidal numbers, the Pell Equation, the unsolved Last Theorem of Fermat, and many other aspects of number theory, simply by learning how to work with them in solving hundreds of mathematical puzzle problems. The text is extremely clear and easy to follow, and it bears convincing evidence of the author's deep sense of humor and his outstanding ability to lure the reader through even the most difficult trails by skillfully revealing their fascination. The problems distributed throughout the book are explained in the final chapter and there is also a supplementary chapter containing 100 problems and their solutions, many original. There are over 100 tables. The appeal of these stimulating puzzles lies in their ready comprehensibility and the fact that only high school math is needed to master the fundamental theory presented by the author. This theory is itself interesting and of use to the more serious math student, but it may be omitted by lay readers without diminishing the book's challenge or detracting from the pleasure-giving nuggets it contains.