What's in Workout 5A?

The workout series of courses consists of students’ most curious math problems, explanations, as well as abundant opportunities to practice

Workout 5A features math questions around Module 5. It consists of 8 daily workouts and 2 weekly exams, which can be finished in 2 weeks. The questions all come from Prof. Loh's online and offline math talks, connected to the knowledge points in Module 3. 

Want to practice the skills you learn in Module 5? Come and challenge yourself in the Workout 5A!

Who Should Take This Course

This course is for students looking for a fun, challenging, and systematic introduction to the fascinating world of Combinatorics, which is not covered in depth in most school curricula, but which appears throughout middle and high school math competitions.

It is recommended for students who have completed Module 5.

At the same time, even high school students (who have not yet taken classes outside of school in Combinatorics) will learn a significant amount.


  Po-Shen Loh 


  • Founder of NOVID, first anonymous contact tracing app against COVID-19 in the USA (2020-present)

  • Carnegie Mellon University, Professor of Mathematics (2010-present)  
  • National Coach of USA International Mathematical Olympiad (IMO) team (2014-present)


  • Princeton University, Ph.D., Mathematics, 2010
  • Cambridge University, Master of Advanced Study in Mathematics with Distinction, 2005 
  • California Institute of Technology, Bachelor of Science with Honor, Mathematics, 2004

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