Competition Math Arena
Endless original olympiad problems with instant, verified solutions — free while in beta.
🌟 Problem of the Day
🏆 Arena Cup
Timed weekly contest + rating change
Save your progress
Create a free account to track your streak, XP, and which topics you've mastered.
🧗 Learning path
Climb from school level to the Olympiad, step by step
Choose a category
Levels: easy = curriculum groundwork; medium-hard = entry olympiad (POSN camp 1). The TMO/IMO bands sit in the mock exams below.
Number Theory
12 topics
- Units digit of powers
- Modular exponentiation
- Power towers (iterated Euler)
- Counting divisors
Algebra
7 topics
- Vieta's formulas
- Sum of cubes of roots
- Systems of equations
- Arithmetic series
Combinatorics
5 topics
- Binomial coefficients
- Stars and bars
- Lattice paths
- Inclusion–exclusion
Diophantine Equations
5 topics
- Simon's Factoring Trick
- Difference of squares
- Linear Diophantine
- Pell's equation
Geometry
20 topics
- Right-triangle area
- Rectangle perimeter
- Missing triangle angle
- Pythagorean hypotenuse
🏆 Practise by exam level
A mixed set at a whole competition level — not just one topic.
School level
1–2 steps, one idea, small numbers.
≈ POSN Camp 1
3–4 steps, two ideas mixed, a little casework.
≈ POSN Camp 2 / IPST
4–5 steps, needs a named theorem, several cases.
≈ Thai MO (national)
5+ steps, needs a genuine insight.
≈ IMO (international)
Named theorems only: Pell, Frobenius, Kummer, order mod n.
How it works
Pick a category and topic that you want to train.
Read the problem, type your answer, and check it.
See the full worked solution, then get a new problem — it never runs out.
Ready to put it all to work?
Always-correct worksheets, a full classroom system, and the paperwork — all in one place. Start free.