Natural numbers are the oldest human inventions. This volume describes their nature, laws, history and current status. The first five chapters contain not only the basics of elementary number theory for the convenience of teaching and continuity of reading, but also many latest research results. For the first time in history, the Chinese Remainder Theorem is renamed the Qin Jiushao Theorem to give him the full credit for his establishment of this famous theorem in number theory. Chapter 6 is about the fascinating congruence modulo an integer power, and Chapter 7 introduces a new problem extracted by the author from the classical problems of number theory, which is out of the combination of additive number theory and multiplicative number theory. In this volume, there is supplementary material after each section to broaden the reader’s knowledge and imagination. It either discusses the rudiments of some aspects or introduces new topics, such as the perfect number problem, Goldbach’s conjecture, the twin prime conjecture, the 3x + 1 problem, Waring’s problem, Catalan’s conjecture, Euler’s conjecture, Fermat’s Last Theorem, etc. Key Features: o This is a book on natural numbers, which can be partially or fully understood by every reader with secondary or higher education o It is an entry level book on basic number theory, but is also an academic monograph that contains wonderful questions and profound results o It can also be read by mathematics majors, graduate students, and researchers o The book contains many illustrations and tables

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