Synopsis Encyclopaedia of Number Theory gives an undergraduate-level introduction to number theory, with the emphasis on fully explained proofs and examples; exercises are integrated into the text. In addition to a careful presentation of the standard material usually taught in a first course in number theory, this book includes chapters on divisibility, prime numbers and modular arithmetic suitable for first or second year students as an introduction to the methods of pure mathematics. Elementary ideas about groups and rings are also discussed in units, quadratic residues and arithmetic functions with applications to enumeration and cryptography. This new volume presents a self-contained introduction to number theory, requiring background knowledge only of some simple properties of the system of integers. Each topic included in the chapters are important for degree students of all Indian university.