Real-Life Good Will Hunting – Chinese Delivery Man Discovers Simpler Solution to Complex Math Problem

Yu Jianchun, A Chinese migrant worker from Henan province with no former mathematical training and no college degree, is being hailed as a real-life version of Will Hunting, the character played by Matt Damon in the 1997 Oscar-winning film “Good Will Hunting”, after finding an alternative method to verify Carmichael numbers.

Carmichael numbers, also known as “pseudo primes”, are large numbers that only appear to be prime numbers, which are only divisible by one and themselves. They are used for credit card encryption and online payments, among other things. There are examinations that can be done to find out which numbers are prime and which are Carmichael numbers, but it’s tricky work. Apparently, a young mailman with no studies in advanced mathematics has just come up with a simpler way to verify Carmichael numbers.


33-year-old Yu Jianchun says he worked on his solution for the last eight years, relying solely on his intuition and his innate sensitivity to numbers. “I made my discoveries through intuition, Yu told China Daily. “I would write down what I thought when inspiration struck about the Carmichael.” And he did it all in his free time, because he had a full time job working as a delivery man for a logistics company. Whenever he had the chance, he stopped by the local and learn more about his passion, math.

After verifying his solution to the Carmichael numbers, Yu apparently wrote several universities about it, but they wouldn’t give him the times of day, because he was just a delivery man with no formal studies in mathematics. But he recently got the chance to present them at Zhejiang University, after professor Cai Tianxin sent him an invitation. On June 13, he presented his proof, along with solutions to four other complex math problems. His way of verifying Carmichael numbers stunned the attendance, including Cai Tianxin, who later told reporters that Yu’s proof was much more efficient than the traditional one.

Photo: Cai Tianxin

“It was a very imaginative solution,” Tianxin said. “He has never received any systematic training in number theory nor taken advanced math classes. All he has is an instinct and an extreme sensitivity to numbers,” the mathematics professor added about the unlikely math genius.

News of Yu Jianchun’s achievements has reached mathematics experts all over the world. William Banks, a mathematician at the University of Missouri who also worked on Carmichael numbers, told CNN that he was excited about the new solution. “There have been additional theoretical results in this area — including several by myself and my co-authors — but these are all variations on a theme,” he said. Yu’s proof, however, is completely different to the classic algorithm used since 1910, when R. D. Carmichael found 15 of these psudo primes.

Photo: Weibo

The young delivery man is being praised as a hero in China, and he’s even received job offers from large companies like investment firm Silk Road Holding Group. They’d love to have him working as a statistics expert. However, for the moment, Yu seems more concerned with finding a girlfriend than building a career. “I want to have my own family first and then comes math,” he said in an interview.

Another impressive thing about the remarkable young man is his modesty. “I’m slow-witted,” he says. “I need to spend far more time studying math problems than others. Although I am sensitive to numbers, I barely have any knowledge about calculus or geometry.”Well, others didn’t find a solution to a complex math problem, you did.

Photo: Cai Tianxin

When asked what he thought about the world comparing him to Mat Damon’s character in the film Good Will Hunting – a young janitor working at the Massachusetts Institute of Technology who who solves a complex math problem – Yu Jianchun didn’t know what to say, because he hasn’t seen it. He’s curious about it, though. If you haven’t seen it either, do it, it’s a really good film.