Shanghai, 2026
The IMO sets three problems on each of two consecutive mornings, each marked out of seven by coordinators who negotiate every point with the team leaders. A seven means a complete and rigorous solution. Forty-two means six of them.
Lee produced that in Shanghai in 2026. The individual results table for the year places him at the top of the standings, because no contestant can score higher; the only competitors level with him are the other perfect papers, if there were any.
From thirty-six to forty-two
In 2025 he had scored 36 and won a gold medal. That means five complete solutions and substantial progress on the sixth — a result most national teams would count as their best of the year.
The step from 36 to 42 is the hardest six points in mathematics competition. Gold medals are won by solving the problems that most of the field can eventually solve; a perfect score requires the one problem each year that is designed to defeat almost everybody, usually the third or the sixth on the paper.
What the olympiad asks
The problems come from algebra, combinatorics, geometry and number theory. They require no university machinery — nothing beyond school syllabus content, in principle — which is exactly what makes them hard: there is no formula to apply, only the construction of an argument nobody has shown you.
Marks are awarded for proof, not for answers. A contestant who reaches the right conclusion by an incomplete argument does not get seven, which is why perfect scores are rare even among competitors who solve everything in the informal sense. Every point is agreed between the markers and the team leaders in coordination sessions that can run for hours over a single line of reasoning.
South Korea at the top
South Korea has been one of the strongest olympiad nations for two decades, and Lee is not its first perfect scorer: the 2016 individual results record a 42 out of 42 by Junghun Ju, who had finished third in the world the previous year.
National selection is its own filter. Each country sends at most six students, chosen through domestic olympiads and training camps, so a contestant who arrives at the IMO has already been ranked among the best few mathematically gifted teenagers in the country. Beating that field is a prerequisite for sitting the paper at all.
What is documented — and what is not
Documented by the IMO's official records: a perfect 42 at the 2026 olympiad in Shanghai, and a gold medal with 36 points in 2025, both for South Korea.
Not documented in these sources: his age, his school, his university plans, whether he competed in earlier years, and anything at all about his life outside the competition. The IMO database is deliberately austere — it holds scores, ranks and medals per contestant, and no biography. Nothing has been added here that the tables do not support.
| Person | Country | Milestone | Age / Stat |
|---|---|---|---|
| Hyeonjun Lee | South Korea | A perfect score at the International Mathematical Olympiad | — |
| Junghun Ju | South Korea | A perfect score at the International Mathematical Olympiad | — |
| Amber Li | Australia | Three consecutive EGMO gold medals | — |
| Aida Mitroi | Romania | Three consecutive EGMO gold medals | — |
| Alisa Volkova | Russia | She solved five of the six problems outright and finished twelfth in the w | — |
What is documented — and what is not
✓ Documented
- He scored a perfect 42 out of 42 at IMO 2026 in Shanghai.
- He won gold with 36 points at IMO 2025.
- He competed for South Korea.
- Both results appear in the IMO's official results database.
? Unverified, disputed or wrong
- His age, school and birth year.
- Whether he competed at the IMO before 2025.
- His university plans or later career.
- Any public statements or interviews.
Questions people ask about Hyeonjun Lee
What did Hyeonjun Lee score at the IMO?
A perfect 42 out of 42 in 2026, in Shanghai, after winning gold with 36 points in 2025.
How rare is a perfect IMO score?
Rare enough that it is the headline result of any olympiad. It requires complete, rigorous solutions to all six problems across two four-and-a-half-hour papers.
How old is Hyeonjun Lee?
The IMO database does not publish ages, and the sources used here give none.
Which country does he represent?
South Korea, one of the strongest teams in the competition.
What subjects do IMO problems cover?
Algebra, combinatorics, geometry and number theory — with no calculus or university-level machinery required, which is what makes them difficult.
Has South Korea had other perfect scores?
Yes. The 2016 individual results record a 42 out of 42 by Junghun Ju.
Is Hyeonjun Lee on Wikipedia?
The research record finds no article under his name. His results are held in the IMO's official contestant database.
Where is he now?
No source used here says. The official record stops with his 2026 result.
Quick quiz: how well do you know Lee’s story?
Where was the 2026 International Mathematical Olympiad held?
What did Hyeonjun Lee score in 2025?
How many problems are set at the IMO?
Sources
- Hyeonjun Lee — IMO contestant results — International Mathematical Olympiad, 2026
- IMO 2026 individual results — International Mathematical Olympiad, 2026
- IMO 2025 individual results — International Mathematical Olympiad, 2025
- IMO 2016 individual results — International Mathematical Olympiad, 2016
Checked by the Geniuses.club editorial team. Ages are given as of September 2026.
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