SHANGHAI -- People all over China are racking their brains to recall high school knowledge, as online live streaming apps woo users with stunning cash prizes in quiz shows.

Mobile apps offer prizes between 100,000 yuan ($15,500) and 5 million yuan for a live streaming quiz of 12 questions. Participants who give all the correct answers split the jackpot.

In a show, a host, often a household celebrity, presents questions, waiting until participants give their answers. Each online contestant has 10 seconds to answer a question, with each show taking around 30 minutes.

The questions derive from a wide range of topics such as traditional Chinese poems, basic mathematics, physics, chemistry and biology.

Live-streamed quiz shows came under spotlight after Wang Sicong, online celebrity and son of Wanda Group chairman Wang Jianlin, announced a prize on a quiz app called Chongdingdahui, translated as "race to the top," on Jan. 3. Other apps Huajiao and Xigua quickly followed suit.

To attract new users, the apps offer "reborn cards" to newcomers and those who invited newcomers to join. A reborn card enables a contestant who gives a wrong answer to have an extra chance to continue the quiz.

Shanghai-based Xiao Yi was invited by one of his former classmates to attend the quiz on the Huajiao app.

"We have formed a WeChat group composed of straight-A students from our former class to pool our wisdom for the answers during the show," he said.

The app has attracted 300 million participants since Jan. 5, and the number of users surged by 20 percent, according to the company, which organized multiple quizzes each day.

Li Jining, a 35-year-old media worker based in Beijing, said she would wait for the quiz as long as she had time after work.

"It was not only the prize that was attractive, but also the thrill that I still could remember what I learned back at high school 20 years ago," she said, adding she was awarded 22 yuan in total for being among winners twice.

The shows have attracted sponsors, bringing in tens of millions of advertising fees to the apps.

"On the Internet, it is all about fighting for the user's time. Hardly any product can keep users attention for 30 minutes like the quiz did. It has expanded possibility for profit," said Yu Dan, a founder of Huajiao.

Huang Bin, a technical director for quiz competition with China's Internet giant Tencent, said since the instant popularity of quiz shows this year, more than 10 companies in online education, news, games and other sectors, had added live-quiz buttons to their apps.

While Internet users are becoming crazy for quiz shows, the apps have tried to make themselves known for "unintentional errors" during the quiz.

On Sunday, Beijing Internet watchdog ordered Huajiao to conduct a thorough inspection on its content as Taiwan and Hong Kong were listed as countries in one of its quiz questions. The app has issued a statement of apology.

Other apps also apologized for their own errors, such as mistaking the obvious origin of the Chinese hamburger (roujiamo) for Jiangsu Province -- it is actually Shaanxi Province. It later compensated users with extra reborn cards.

Chen Liteng, an assistant analyst with China e-commerce research center, said online streaming apps had won many users with the quizzes, but the way of luring users with big cash prizes and celebrities as hosts was not sustainable.

"The mode is perhaps only a short-term thing," he said.