Combinatorics Open 2026
Combinatorics Open
📌 About the Event
Combinatorics Open 2026 is a free, online international mathematics competition designed for pre-university students from anywhere in the world. The competition focuses on combinatorial thinking through problems involving counting, probability, graph theory, invariants, recursion, games and other areas of discrete mathematics. Participants will solve 20 short-answer problems individually within a 90-minute session during a 48-hour worldwide competition window.
ℹ️ Event Details
- Organizer: Combinatorics Open
- Type: International Mathematics Competition
- Mode: Online
- Participation: Individual
- Eligibility: Pre-university students worldwide who have not completed secondary school
- Competition Format: 20 short-answer problems
- Duration: 90 minutes
- Competition Window: 48 hours
- Language: English
📅 Important Dates
- Registration Opens: 12 September 2026
- Sample Problems Published: 21 September 2026
- Problem of the Week Begins: 1 October 2026
- Registration Deadline: 13 November 2026, 5:30 PM IST
- Competition Starts: 14 November 2026, 5:30 AM IST
- Competition Ends: 16 November 2026, 5:29 AM IST
- Problems & Solutions Published: 17 November 2026
- Preliminary Results: 19 November 2026
- Final Results: 24 November 2026
🎯 Eligibility& Rules
- Ties are resolved by comparing performance on the hardest problems, beginning with Problem 20.
- Open to students who have not completed secondary school, regardless of country or grade.
- Students in Grade 10 or below (or equivalent) are eligible for the Junior Ranking.
- Dual-enrolled secondary school students are eligible.
- Participation is individual; no teams.
- Participants must solve 20 short-answer mathematics problems in 90 minutes.
- Calculators, coding, online searches, published references, and outside assistance are not allowed.
- Participants must work independently throughout the contest.
🏆 Benefits for the Participants
- Gold, Silver and Bronze performance designations
- Separate Junior Ranking for Grade 10 and below, or equivalent
- Country Top Scorer recognition for countries with at least five official participants
- Digital certificate for all participants
- Official problems, solutions and results will be made publicly available after the competition