TikTok's founder Zhang has a formula for everything. Can it crack the Supreme Court?

As the court weighs a ban on the video-sharing app in the US, no one has more to lose than Zhang Yiming

- Stu Woo & Raffaele Huang

Zhang Yiming chose a college by calculating which schools were far from home and had a favorable female-to-male ratio for finding love. He bought his first home by devising a formula to identify Beijing's best community.

And he became China's richest person after creating TikTok, the massively popular app built around an algorithm that predicts the videos people would enjoy based on their previous activity.

But 41-year-old Zhang has no formula to guide him through TikTok's biggest challenge yet.

The Supreme Court heard arguments on Friday over the constitutionality of a national-security law that would effectively ban the app in the U.S. Most justices voiced doubts about TikTok's arguments, viewing the law not as a restriction on free speech but instead as targeting its Chinese ownership.

The showdown threatens to unravel Zhang's biggest accomplishment to date, as well as his greatest desire. Zhang has long said his dream is to run a business that is successful even beyond his native land of 1.4 billion people.

"China's internet users account for only one-fifth of worldwide users," he said at a 2016 conference. He concluded there was only one way for his company to compete with the best: "Going global is a must."

Last year, Zhang became China's richest person, with a net worth of about $49 billion, according to the Hurun Research Institute, which studies Chinese wealth. Much of his fortune comes from his stake in TikTok's Beijing-based parent company, ByteDance, which also operates hit Chinese apps. He is ByteDance's single largest shareholder, with a 21% equity stake, and has majority control over the company through shares with extra voting rights.

Born in 1983, Zhang grew up in China's southeastern province of Fujian. His father ran an electronics factory, and his mother was a nurse.

As a middle-schooler, Zhang once said in an interview, he read newspapers cover to cover.