This is a student solutions manual for Elementary Number Theory with Applications 1st edition by Thomas Koshy (2002). Note that the textbook itself is not included in this purchase.
From the back cover of the textbook: Modern technology has brought a new dimension to the power of number theory: constant practical use. Once considered the purest of pure mathematics, number theory has become an essential tool in the rapid development of technology in a number of areas, including art, coding theory, cryptology, and computer science. The range of fascinating applications confirms the boundlessness of human ingenuity and creativity.
Elementary Number Theory captures the author's fascination for the subject: its beauty, elegance, and historical development, and the opportunities number theory provides for experimentation, exploration, and, of course, its marvelous applications.