Six sevens
The official results row is the shortest possible summary of a very long two days: 7, 7, 7, 7, 7, 7. Each of the six problems is marked out of seven, and a seven means a complete and correct solution rather than a good attempt. Nothing in Zhang's paper was left for a marker to judge generously.
The scale of that is easier to see from the rest of the table. The next-highest score in 2025 was 40, held by his compatriot Hongyi Tan. Below that came Qiao Zhang of the United States on 39 and Trong Khai Vo of Vietnam on 38. A gold medal that year required 35 points, which means the gap between the perfect papers and the bottom of the gold band was seven marks.
The other four
Zhang shared first place with four other contestants who also scored 42: Leyan Deng, his own teammate; Warren Bei of Canada; Satoshi Kano of Japan; and Ivan Chasovskikh. Five perfect papers out of 630 is a rate of less than one in a hundred and twenty.
China placing two contestants on a perfect score in the same year is the detail that stands out in the team column. The Chinese results listed in 2025 run Leyan Deng on 42, Hengye Zhang on 42, Hongyi Tan on 40 and Zhenyu Dong on 35, which is a spread from the ceiling down to the gold cut-off.
What a perfect paper requires
The IMO does not set six problems of equal difficulty. Each of the two papers carries one question intended to defeat almost everyone, and the published tables show the effect: at the top of the ranking, most contestants have a string of sevens followed by a low number. The entire ordering of the leaderboard is usually decided by partial credit on those two questions.
A 42 therefore is not simply a very high score. It means the contestant solved both of the problems that were designed to be unsolvable in the time available, in addition to the four that were merely hard. That is why the count of perfect scores is reported every year as a fact about the year rather than about the individuals.
What the table records — and what it does not
The firm facts come directly from the organisers: country, six problem scores, total, rank, medal, year and host location. There is no journalistic intermediary between the event and the record, which is the strongest evidential position a page like this can be in.
The table is also the limit of the record. It publishes no age, no date of birth, no school, no city and no photograph, and nothing in the sources gathered here describes Zhang's route to the team, his earlier competition history, or what he has done since. Those absences are recorded here as absences.
Why perfect scores are counted
The number of 42s in a given year has become a rough measure of how the problems were pitched. In 2024 at Bath, exactly one contestant finished on a perfect score. In 2025 there were five. In 2026 at Shanghai there were seven. The same six-problem format produces very different results depending on how hard the two decisive questions turn out to be.
That context sharpens rather than dilutes the achievement. A perfect paper in any year requires beating the two problems the organisers wrote specifically to stop it happening, and in 2025 fewer than one per cent of the field did so. Zhang's row is one of those five.
| Person | Country | Milestone | Age / Stat |
|---|
What is documented — and what is not
✓ Documented
- Perfect 42 of 42 at IMO 2025, joint 1st, gold medal (official IMO results)
- One of five perfect scores in a field of 630
- Competed for China; Chinese teammates listed on 42, 40 and 35 points
? Unverified, disputed or wrong
- No age, birth year, school or city in these sources
- No record of earlier or later olympiad appearances
- No published information about what he has done since 2025
Questions people ask about Hengye Zhang
What did Hengye Zhang achieve?
A perfect score of 42 out of 42 at the 2025 International Mathematical Olympiad, sharing first place in the world in a field of 630.
How many people scored 42 in 2025?
Five: Hengye Zhang and Leyan Deng of China, Warren Bei of Canada, Satoshi Kano of Japan, and Ivan Chasovskikh.
How old is Hengye Zhang?
No source in this record gives his age or birth year. The IMO results table publishes names, countries, scores, ranks and medals only.
How hard is a perfect score at the IMO?
Rare. One contestant scored 42 in 2024, five in 2025 and seven in 2026, out of fields of roughly 600 to 670.
What score was needed for gold in 2025?
Thirty-five points out of 42, according to the official table.
How did China do in 2025?
The Chinese results listed run Leyan Deng on 42, Hengye Zhang on 42, Hongyi Tan on 40 and Zhenyu Dong on 35, all gold.
Is Hengye Zhang on Wikipedia?
No Wikipedia article was found for him. The source used here is the official IMO results table.
Where is Hengye Zhang now?
No source in this record says. The documented trail is his row in the 2025 results.
Quick quiz: how well do you know Zhang’s story?
What did Hengye Zhang score at IMO 2025?
How many contestants scored a perfect 42 that year?
How many problems does the IMO set?
Sources
- IMO 2025 individual results — International Mathematical Olympiad, 2025
- IMO 2024 individual results — International Mathematical Olympiad, 2024
- IMO 2026 individual results — International Mathematical Olympiad, 2026
Checked by the Geniuses.club editorial team. Ages are given as of September 2026.
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