Meanwhile : The $25 problem

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Meanwhile : The $25 problem

Published: 10 Feb. 2026, 00:05

Audio report: written by reporters, read by AI

Lee Woo Young

The author is an HCMC distinguished professor at the Korea Institute for Advanced Study.

An elderly man in a worn coat and thick horn-rimmed glasses slowly walked to the front of a conference hall. It was a break between sessions, yet no one left their seats. Participants watched in silence, wondering what problem he would present this time.

Approaching a chalkboard in the corner, he wrote down a mathematical problem and added a note beside it: Prize, $25. Attendees hurried to copy the problem. When doing this, his reward would sometimes increase depending on the difficulty. But the money was never the point. Solving one of his problems was itself an honor.

Mathematician Paul Erdős photographed in Budapest, Hungary, in 1992. [WIKIPEDIA]

The man was Paul Erdos (1913–1996), an eccentric mathematician from Budapest who became one of the most prolific figures in the history of mathematics. Over his lifetime, he published more than 1,500 papers and collaborated with more than 500 co-authors.

Erdos was a talkative genius, but also disarmingly naive and often awkward in daily life. In the early 1950s, when the United States was gripped by anti-communist investigations, an immigration officer asked his opinion of Karl Marx. “A great man,” he replied. He was denied entry.

During screening for participation in the Manhattan Project, the U.S.-led nuclear weapons program, he was also rejected. Officials concluded that his talkative nature made it difficult for him to keep secrets. In hindsight, the outcome suited him. He devoted his life to finding good mathematical problems, sharing them with others and working together to solve them.

Erdos disliked staying in one place. A lifelong itinerant mathematician, he had no permanent home or family and traveled through more than 22 countries. At the age of 83, he died while attending a conference in Warsaw.

His final words left a quiet resonance: “I won’t become any more stupid.”

Erdos left behind a remarkable body of mathematical work, but perhaps his greatest legacy was something less tangible. By turning even difficult problems into a form of intellectual play, he inspired generations of mathematicians and students. His small prizes, modest in value, carried a deeper message that discovery itself was the true reward.

In the end, the measure of a life may not lie only in individual achievement, but in the curiosity and energy one awakens in others.

This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.