18.781 Theory of Numbers

Spring 2026

I. Information

Instructor: Ju-Lee Kim
Lecture: Mondays and Wednesdays 11:00 am–12:30 pm at 4-370
Office Hours: Tuesdays 1:00 pm–2:00 pm, Thursdays 1:30 pm–2:30 pm at 2-442

Teaching Assistant: Allen Lin
Office Hours: Fridays 1:30 pm–2:30 pm at 2-255

Teaching Assistant: Oriol Solé Pi
Office Hours: Wednesdays 12:30 pm–1:30 pm at 2-332

Canvas Piazza Gradescope

II. Description

An elementary introduction to number theory with no algebraic prerequisites. Primes, congruences, quadratic reciprocity, diophantine equations, irrational numbers, continued fractions, partitions.

Textbook: Ivan Niven, Hubert Zuckerman, and Hugh Montgomery, An Introduction to the Theory of Numbers, 3rd edition.

III. Grading

Problem Sets 15%

Pset 1 1.25%

Pset 2 1.25%

Pset 3 1.25%

Pset 4 1.25%

Pset 5 1.25%

Pset 6 1.25%

Pset 7 1.25%

Pset 8 1.25%

Pset 9 1.25%

Pset 10 5%

Quizzes 85%

Quiz I 23%

Quiz II 28%

Quiz III 34%

Total 100%

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lowest one dropped

IV. Problem Sets

Problem Set	Released	Due	PDF	Solutions
Problem Set 1	3 Feb 2026	13 Feb 2026	PDF	Solutions
Problem Set 2	14 Feb 2026	20 Feb 2026	PDF	Solutions
Problem Set 3	21 Feb 2026	27 Feb 2026	PDF	Solutions
Problem Set 4	8 Mar 2026	13 Mar 2026	PDF	Solutions
Problem Set 5	14 Mar 2026	23 Mar 2026	PDF	Solutions
Problem Set 6	24 Mar 2026	5 Apr 2026	PDF	Solutions
Problem Set 7	11 Apr 2026	19 Apr 2026	PDF	Solutions
Problem Set 8	18 Apr 2026	26 Apr 2026	PDF	Solutions
Problem Set 9	24 Apr 2026	3 May 2026	PDF	Solutions
Problem Set 10	8 May 2026	12 May 2026	PDF	Solutions

V. Quizzes

Quiz	Date
Quiz I	5 Mar 2026
Quiz II	9 Apr 2026
Quiz III	7 May 2026