Remember more than three thousand binary numbers- Memorize a single pack of cards in 20 seconds- That's what this year's winner of the World Memory Championships had to do. Now in its 20th year, the competition has kicked off in the southern Chinese city of Guangzhou.

A competition to remember - literally! 120 competitors from 22 countries and regions have gathered here, in Guangzhou city.

Over the next three days, they must memorize as much information as possible within a given time. The prize: to become the next Grand Memory Master.

Competition founder, Tony Buzan, believes that everyone can improve their memories. Tony Buzan, founder of World Memory Competition, said, "The frontiers of what the brains can do have been extended. When we look to the horizon at what we can do, what the championships are increasingly saying is there is no horizon, it's infinite."

The competitors will test their mental boundaries by memorizing numbers, abstract images, dates, names and faces, as well as decks of cards, all against the clock.

China, the host nation, is one of the strongest competitors. Wang Feng has already made the record books, by memorizing 2660 numbers within an hour.

Wang Feng, reigning World Memory champion, said, "I won the Championship last year. To defend the title, I had to practice 5 to 6 hours every day over the last three months."

This year, more than a quarter of the competitors are female - the oldest being a ripe 74. Many of the competitors believe the memorizing techniques they practice help them achieve other goals in life. But for now, their focus is all in their heads.