Lu Chao took 24 hours and 4 seconds to recite 67,890 digits of pi from memory.

Quick Scoop: Lu Chao’s Pi Marathon

Lu Chao, a Chinese graduate student, set a Guinness World Record by reciting pi to the 67,890th decimal place in a single, continuous attempt. According to an interview on a pi ranking site, he confirmed that the official recitation time was 24 hours and 4 seconds with no breaks allowed longer than 15 seconds between digits.

Key Facts

  • Duration of recitation: 24 hours 4 seconds.
  • Digits correctly recited: 67,890 decimal places of pi.
  • Break rules: No pauses longer than 15 seconds between numbers, meaning no proper food or toilet breaks.
  • Training time: He reported spending about one year to memorize 100,000 digits of pi.

How Long Did It Take Lu Chao to Recite 67,890 Digits of Pi?

In his own words from an interview on the Pi World Ranking List, Lu Chao states:

“It took me 24 hours 4 seconds to recite to the 67,890th place of Pi.”

News reports at the time also describe that he completed the feat in “just over one day,” specifying 24 hours and 4 minutes or “24 hours and 4 minutes” in some write-ups, which appears to be a reporting inconsistency versus his precise figure of 24:00:04. The most authoritative timing is the figure Lu Chao himself gives: 24 hours 4 seconds.

Mini Timeline of the Feat

  • He began seriously training in 2004, practicing more than 10 hours a day during vacation periods.
  • He completed the record recitation in November 2005; news of the confirmation was reported the following year.
  • During the attempt, a strict rule required that the time between spoken numbers never exceed 15 seconds.

Meta Description (SEO)

Lu Chao’s world record pi recitation: discover how long it took Lu Chao to recite 67,890 digits of pi (24 hours and 4 seconds), what rules he followed, and how he prepared for this extreme memory challenge.

TL;DR: It took Lu Chao 24 hours and 4 seconds to recite 67,890 digits of pi without error under Guinness World Records rules.

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