What 42 out of 42 means
Each IMO paper carries three problems and four and a half hours. A contestant who scores seven on a problem has produced a complete, rigorous solution; six means a solution with a gap the coordinators judged small. Forty-two means six sevens: nothing incomplete, nothing hand-waved, across two mornings in a foreign city.
Gold medals are routinely won without a perfect paper. Forty-two is a different category of result, and it is the reason the official results tables are the only source this page needs: they record, permanently and per contestant, exactly what was scored on each problem.
Third in the world at 40
The previous year he had scored 40 and finished third overall in the individual standings. Two points across six problems separated him from a perfect paper in 2015.
That is arguably the more impressive half of the record. A single perfect score can follow a favourable problem set; two consecutive years at 40 and 42 means a contestant who solved essentially every problem the competition put in front of him across two entirely different papers.
The competition itself
The IMO is the oldest and largest of the international science olympiads. National teams of up to six students qualify through their own selection systems, and the problems are drawn from algebra, combinatorics, geometry and number theory — elementary in the technical sense, in that no university machinery is required, and extremely hard in practice.
South Korea has been among the strongest teams in the world for two decades, which makes selection for it a severe filter in its own right. A Korean contestant has already beaten a national field before arriving at the competition, and then sits the same paper as every other country's best six students on the same morning.
What the official record holds
The IMO publishes a page for every contestant who has ever competed. Ju's carries his scores, his ranks and his medals; the 2015 and 2016 individual results pages place those numbers in context against everyone else who sat the same papers.
What the database deliberately does not hold is a biography. There is no age, no school, no photograph and no later career. For a competitor whose public record is entirely mathematical, that is the whole file — and it is also the reason the result is trustworthy. Nothing here depends on a press release, an interview or a claim made on anyone's behalf.
What is documented — and what is not
Documented by the IMO's official site: a perfect 42 in 2016, and 40 points for third place overall in 2015, both for South Korea.
Not documented in these sources: his age, his school, his university, whether he competed in other years, and anything he has done since 2016. Nothing about his personal life appears in the material used for this page, and none has been invented for it.
| Person | Country | Milestone | Age / Stat |
|---|
What is documented — and what is not
✓ Documented
- He scored a perfect 42 out of 42 at IMO 2016.
- He scored 40 points and finished third overall at IMO 2015.
- 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 in years other than 2015 and 2016.
- His university and later career.
- Any interviews or public statements.
Questions people ask about Junghun Ju
What did Junghun Ju score at the IMO?
A perfect 42 out of 42 in 2016, having scored 40 points and finished third in the world in 2015.
How hard is a perfect IMO score?
It requires complete solutions to all six problems across two four-and-a-half-hour papers. Most gold medals are won well below that mark.
How old is Junghun Ju?
The IMO database does not publish ages, and the sources used here give none.
Which country did he represent?
South Korea, one of the strongest teams in the competition.
How is the IMO scored?
Six problems over two days, each marked out of seven, for a maximum of 42 points.
Is Junghun Ju 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 competition results.
Did he win a gold medal?
His scores of 40 and 42 place him at the very top of the individual standings in both years. The official contestant page holds the medal record for each year.
Quick quiz: how well do you know Ju’s story?
What is the maximum score at the IMO?
What did Junghun Ju score in 2015?
How many problems are set at the IMO?
Sources
- Junghun Ju — IMO contestant results — International Mathematical Olympiad, 2016
- IMO 2016 individual results — International Mathematical Olympiad, 2016
- IMO 2015 individual results — International Mathematical Olympiad, 2015
Checked by the Geniuses.club editorial team. Ages are given as of September 2026.
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