OTIS (officially OTIS Math LLC) is a proof-based olympiad training program. (Students not yet ready for proofs may be interested in my list of mentors and programs.)

About OTIS#

Syllabus#

Other documents#

Read the above syllabus first if you’re new to OTIS.

• Video tour of website
• List of topics (now featuring artwork)
• Example materials from each of the three difficulty tracks:
  • B-level track handout (easiest track)
  • D-level track handout and solutions
  • Z-level track handout (hardest track)

• Example practice exam: JMO, USAMO, and solutions
• OPAL puzzle hunt

The OTIS Excerpts#

Around the start of 2019, I posted publicly a collection of 202 problems and solutions based on materials for OTIS. This mini-book was named The OTIS Excerpts. It’s designed to mostly be beginner-friendly though some of the chapters are more challenging.

Application — Year XI (2025-2026)#

You can submit late applications for the 2025-2026 school year up until the end of April 2026. See instructions below.

• Application homework and instructions
• Application portal at apply.evanchen.cc

The application portal is a brand-new experiment (released November 2025) and I’m hoping it makes the application process a little smoother¹. Send me bug reports as you find them.

Who can apply (aka, everyone)#

OTIS is open to anyone, including international students from all countries. There is no age restrictions at all (younger than 9th grade or older than 12th grade are both OK, nor do you have to be in school). Students from minorities and underrepresented groups are especially encouraged to apply. (I promise I don’t bite.) Full financial aid is available for all applications (even late) and admissions is need-blind.

Admissions are only done to ensure students have enough mathematical background and writing ability (due to sheer number of students, there is no “grading”), understand English, and are able to learn from Evan-style writing. In particular, admissions is not a merit-based competition. See the application PDF for more details.

People#

Currently Evan Chen (Game Master) is the only employee.

Photos#

Authorized third-party instructors

Generally, OTIS is internal use only. In some cases (usually only by invitation for people I know) I permit some private third-party instructors to borrow the OTIS platform for their own use. A list of instructors who have done this at least once before (parentheses indicated years as a student in the program):

Abdullahil Kafi (VII-VIII); Adhitya Mangudy; Archit Manas (VII-VIII); Galin Totev; Jeffrey Kwan (IV-V); Kanav Talwar (IX); Márton Borbényi; Michael Ren (I-II); Noah Walsh (V-VI); Rushil Mathur (VII-VIII); Anant Mudgal (III); Ankan Bhattacharya; Anushka Aggarwal (V); Arindam Bhattacharyya (V); Atul Nadig (VII); CJ Quines; Dávid Matolcsi; Gopal Goel (IV-V); Howard Halim (III-IV); James Lin; Pranjal Srivastava (IV); Ram Goel (V-VII); Reed LaFleche; Rohan Goyal (V); Sanjana Das (VI); Xinke Guo-Xue; Zack Chroman (II-III); Zoltan Gyenes.