This is a nice little book (290 pages), which can be used as course litterature for an introductory course in number theory or a by-side reading for somebody taking a first course. It's exposition is so pedagogical and clear that I could study the book from the beginning to the end on my own without help. This is pretty rare for a mathematical book. It covers not only the basic subjects likes divisibility, primes and congruences but more advanced subjects like Euler's functions, quadratic residues, Riemann zeta function as well. there is even a final chapter on Fermat's Last Theorem, which is quite accessible. I would not hesitate to recommend this book to anybody starting to study number theory. Finally it contains complete solutions to all exercises.