--- title: Good Will Hunting: Chinese Mailman Becomes Math Whiz description: A mailman in China has found a simple way to solve complex math problems, just like Matt Damon's character from Good Will Hunting canonical: https://time.com/4413249/good-will-hunting-chinese-mailman-math/ author: Julissa Higgins article:opinion: false article:content_tier: free article:published_time: 2016-07-19T18:21:13.000Z article:modified_time: 2026-02-22T23:22:12.662Z article:section: World og:title: Mailman Turned Math-Whiz Is the Chinese Equivalent of ‘Good Will Hunting’ og:description: It's a real-life 'Good Will Hunting' og:url: https://time.com/4413249/good-will-hunting-chinese-mailman-math/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltde093bcdab65f2d0/6988d9b9bc6cfc69913e2a3c/time-logo.jpg?branch=production og:image:width: 1200 og:image:height: 675 og:image:alt: TIME og:type: article twitter:card: summary_large_image twitter:title: Mailman Turned Math-Whiz Is the Chinese Equivalent of ‘Good Will Hunting’ twitter:description: It's a real-life 'Good Will Hunting' twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltde093bcdab65f2d0/6988d9b9bc6cfc69913e2a3c/time-logo.jpg?branch=production --- # Mailman Turned Math-Whiz Is the Chinese Equivalent of _Good Will Hunting_ by [Julissa Higgins](/author/julissa-higgins/) ## Julissa Higgins Jul 19, 2016 6:21 PM CUT by [Julissa Higgins](/author/julissa-higgins/) ## Julissa Higgins Jul 19, 2016 6:21 PM CUT A migrant worker who works as a mailman in China has found a simple way to solve complex math problems, just like Matt Damon’s character from _Good Will Hunting —_ and it’s earn him a job offer from a private investment group. Yu Jianchun discovered new a way to find Carmichaels, also known as “pseudoprimes,” which are large numbers that appear to be prime, but in fact are not. He has no college degree or formal advanced mathematics training, but relies mostly on his intuition to solve the problems, he said. “I made my discoveries through intuition,” Yu [said](http://www.chinadaily.com.cn/china/2016-06/23/content%5F25813818.htm "undefined") in an interview with China _Daily_. “I would write down what I thought when inspiration struck about the Carmichael.” Carmichaels have real-world applications and are commonly used for credit card encryptions and online shopping. While his discoveries have not been verified, Yu’s achievement gained him international recognition and has stunned math experts. After giving a demonstration of his discoveries at Zhejiang University, using only what he recalled from pure memory as his notes, he has been offered a statistics position at Silk Road Holding Group, an investment company in China. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/4413249/good-will-hunting-chinese-mailman-math/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/4413249/good-will-hunting-chinese-mailman-math/"},"headline":"Mailman Turned Math-Whiz Is the Chinese Equivalent of Good Will Hunting","datePublished":"2016-07-19T18:21:13.000Z","dateModified":"2026-02-22T23:22:12.662Z","description":"It's a real-life Good Will Hunting","url":"https://time.com/4413249/good-will-hunting-chinese-mailman-math/","keywords":["movies","viral","China"],"thumbnailUrl":"","author":[{"@type":"Person","name":"Julissa Higgins","jobTitle":null,"url":"https://time.com/author/julissa-higgins/"}],"articleSection":"World","image":[],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/world/","name":"World"}},{"@type":"ListItem","position":2,"item":{"@id":"https://time.com/4413249/good-will-hunting-chinese-mailman-math/","name":"Mailman Turned Math-Whiz Is the Chinese Equivalent of Good Will Hunting"}}]}] ```