Undergraduate Mathematics Problem Solving Seminar

Fall 2013



Seminar Info

Organizers: Lev Borisov (borisov@math.rutgers.edu), Swastik Kopparty (swastik.kopparty@gmail.com (Note: swastik.kopparty@rutgers.edu has been unreliable lately))

Meeting time and place: Thursday 1:40 3:00, Allison Road Classroom Building 212


Applying and Registering: To apply for admission to the seminar, submit a Honors Special Permission Application Form to the undergraduate office (Hill 303).


This is a seminar in mathematical problem solving.  It is aimed at undergraduate students who enjoy solving mathematical problems in a variety of areas, and want to strengthen their creative mathematical skills, and their skills at doing mathematical proofs.


A secondary goal of this seminar is to help interested students prepare for the William Lowell Putnam Undergraduate Mathematics Competition , which is an annual national mathematics competition held every December. Any full-time undergraduate who does not yet have a college degree is eligible to participate in the exam. (However, you are free to participate in the seminar without taking the exam, and vice versa.)



The meetings of the seminar will be a mixture of presentations by the instructors, group discussions of problems, and student presentations of solutions/ideas.

The seminar qualifies as an honors seminar for the honors track . Students who have taken the seminar previously may not register for it, but are very welcome to attend.


All students taking the seminar are expected to:

         Attend regularly.

         Participate actively in group problem solving.

         Take their turn presenting a problem solution to the class.

         Read text book chapter to be covered in advance of the seminar meeting.

         Work on some of the assigned problems and turn in a carefully written solution for at least one problem per week.


Some appetizers:

         When you multiply the numbers 1, 2, 3, , 400, how many trailing 0s does the answer have?

         Suppose we have a matrix of distinct numbers and we sort each row in increasing order, then we sort each column in increasing order. Are the rows necessarily still in increasing order?

         Determine (without using a calculator) which is larger: or ?

         Find the remainder when 123456789 is divided by 91 (without using a supercomputer).

         Show that in any sequence of n2+1 distinct integers, there is either an increasing subsequence or a decreasing subsequence of size n+1.

         Suppose you have a n red points and n blue points in the plane. Can you pair up the red points with the blue points (each red point is paired with one blue point) so that all the line segments between the pairs are nonintersecting?


Seminar Problem Sets

Every week you should turn in a complete formally-written solution (or clear explanation of your good faith attempt) for at least ONE problem


         September 5: miscellaneous problems

         September 12: the pigeon-hole principle

         September 19: polynomials

         September 26: 2-way counting and inclusion-exclusion

         October 3: analysis and geometry

         October 10: inequalities

         October 17: number theory

         October 24: miscellaneous

         October 31: miscellaneous

         November 7: miscellaneous

         November 14: some old Putnam problems