The catalog description for Elementary Number Theory (MATH 3120) is: "Introduces number theory, treating divisibility, congruencies, linear Diophantine equations, and quadratic residues. Some history of the development of the discipline also is included." The prerequisite is Mathematical Reasoning (MATH 3000). This descriptions are based on the ETSU 2020-21 Undergraduate Catalog.

Copies of the classnotes are on the internet in PDF format as given below. The "Examples, Exercises, and Proofs" files were prepared in Beamer and they contain proofs of the results from the class notes. The "Printout of Examples, Exercises, and Proofs" are printable PDF files of the Beamer slides without the pauses. These notes and supplements have not been classroom tested (and so may have some typographical errors).

• Preface. Preface notes
• Section 1. Integers. Section 1 notes (This section includes The Division Algorithm and The Euclidean Algorithm.)
• Supplement. Examples, Exercises, and Proofs from Section 1. Beamer file of Section 1 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 1. Print file of Section 1 proofs and examples
• Section 2. Unique Factorization. Section 2 notes (This section includes a proof of the Fundamental Theorem of Arithmetic.)
• Supplement. Examples, Exercises, and Proofs from Section 2. Print file of Section 2 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 2. PDF
• Section 3. Linear Diophantine Equations. Section 3 notes
• Supplement. Examples, Exercises, and Proofs from Section 3. Beamer file of Section 3 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 3. Print file of Section 3 proofs and examples
• Section 4. Congruences. Section 4 notes
• Supplement. Examples, Exercises, and Proofs from Section 4. Beamer file of Section 4 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 4. Print file of Section 4 proofs and examples
• Section 5. Linear Congruences. Section 5 notes (This section includes The Chinese Remainder Theorem.)
• Supplement. Examples, Exercises, and Proofs from Section 5. Beamer file of Section 5 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 5. Print file of Section 5 proofs and examples
• Section 6. Fermat's and Wilson's Theorems. Section 6 notes (This section includes biographical information on Pierre de Fermat.)
• Supplement. Examples, Exercises, and Proofs from Section 6. Beamer file of Section 6 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 6. Print file of Section 6 proofs and examples
• Section 7. The Divisors of an Integer. Section 7 notes
• Supplement. Examples, Exercises, and Proofs from Section 7. Beamer file of Section 7 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 7. Print file of Section 7 proofs and examples
• Section 8. Perfect Numbers. Section 8 notes
• Supplement. Examples, Exercises, and Proofs from Section 8. Beamer file of Section 8 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 8. Print file of Section 8 proofs and examples
• Section 9. Euler's Theorem and Function. Section 9 notes
• Supplement. Examples, Exercises, and Proofs from Section 9. Beamer file of Section 9 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 9. Print file of Section 9 proofs and examples
• Section 10. Primitive Roots. Section 10 notes
• Supplement. Examples, Exercises, and Proofs from Section 10. Beamer file of Section 10 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 10. Print file of Section 10 proofs and examples
• Section 11. Quadratic Congruences. Section 11 notes
• Supplement. Examples, Exercises, and Proofs from Section 11. Beamer file of Section 11 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 11. Print file of Section 11 proofs and examples
• Section 12. Quadratic Reciprocity. Section 12 notes
• Supplement. Examples, Exercises, and Proofs from Section 12. Beamer file of Section 12 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 12. Print file of Section 12 proofs and examples
• Section 13. Numbers in Other Bases. Section 13 notes
• Supplement. Examples, Exercises, and Proofs from Section 13. Beamer file of Section 13 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 13. Print file of Section 13 proofs and examples
• Section 14. Duodecimals. Section 14 notes
• Section 15. Decimals. Section 15 notes
• Supplement. Examples, Exercises, and Proofs from Section 15. Beamer file of Section 15 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 15. Print file of Section 15 proofs and examples
• Section 16. Pythagorean Triangles. Section 16 notes
• Supplement. Examples, Exercises, and Proofs from Section 16. Beamer file of Section 16 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 16. Print file of Section 16 proofs and examples
• Supplement to Section 16. The Group of Primitive Pythagorean Triples. Group of Primitive Pythagorean Triples notes
• Section 17. Infinite Descent and Fermat's Conjecture. Section 17 notes (This section includes results concerning the sum of three cubes which equals a cube.)
• Supplement. Examples, Exercises, and Proofs from Section 17. Beamer file of Section 17 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 17. Print file of Section 17 proofs and examples
• Supplement. Fermat's Last Theorem-History. Fermat's Last Theore-History notes
• Section 18. Sums of Two Squares. Section 18 notes
• Supplement. Examples, Exercises, and Proofs from Section 18. Beamer file of Section 18 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 18. Print file of Section 18 proofs and examples
• Section 19. Sums of Four Squares. Section 19 notes
• Supplement. Examples, Exercises, and Proofs from Section 19. Beamer file of Section 19 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 19. Print file of Section 19 proofs and examples
• Section 20. x² − Ny² = 1. Section 20 notes
• Supplement. Examples, Exercises, and Proofs from Section 20. Beamer file of Section 20 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 20. Print file of Section 20 proofs and examples
• Section 21. Bounds for π(x). Section 21 notes
• Supplement. Examples, Exercises, and Proofs from Section 21. Beamer file of Section 21 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 21. Print file of Section 21 proofs and examples
• Section 22. Formulas for Primes. Section 22 notes (This section includes "Bertrand's Postulate.")
• Supplement. Examples, Exercises, and Proofs from Section 22. Beamer file of Section 22 proofs and examples
• Supplement. Printouts of Examples, Exercises, and Proofs from Section 22. Print file of Section 22 proofs and examples
• Supplement. The Prime Number Theorem-History. Prime Numer Theorem-History notes
• Supplement. The Riemann Hypothesis-History. Riemann Hypothesis-History
• Section 23. Additional Problems.
• Appendix A. Proof by Induction.
• Appendix B. Computer Problems.
• Appendix C. Factor Table for Integers Less Than 10,000.

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