This book is a revised and greatly expanded version of our book Elements of Number Theory published in 1972.As with the first book the primary audience we envisage consists of upper level underfraduate mathematics majors and graduate students.We have assumed some familiarity with the material in a standard undergraduate course in abstract algebra.  此书为英文版!This book is a revised and greatly expanded version of our book Elements of Number Theory published in 1972.As with the first book the primary audience we envisage consists of upper level underfraduate mathematics majors and graduate students.We have assumed some familiarity with the material in a standard undergraduate course in abstract algebra. 此书为英文版!