Q:
# How many digits of pi have been calculated?

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### Quick Answer

**According to Numberworld, 12.1 trillion digits of pi have been calculated, as of December 2013.** This was achieved after 94 days of computation; however, 12 of those days were lost to hardware issues. The previous calculation that achieved 10 trillion digits took 371 days to complete two years prior.

Credit:
The Washington Post
The Washington Post
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As of 2014, the world record for digits of pi memorized is held by Chao Lu from China. He spent four years practicing and was able to recite 67,890 digits of pi from memory. The recitation happened on Nov. 20, 2005, took just over 24 hours to complete and was documented on 26 video tapes.

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Q:
## What is pi?

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Full Answer >**Pi is the ratio of a circle's circumference to its diameter.**The number pi, symbolized by a Greek letter, has a constant value that approximately equals 3.14. The distance around any circle when divided by its diameter always gives this exact result.Filed Under: -
Q:
## Why does pi not have units?

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Full Answer >**Pi does not have units because it is a number, not a measurement.**However, pi is sometimes treated like a unit when referring to angle measurements because the actual unit, radians, is a length divided by length and is therefore dimensionless.Filed Under: -
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## What does pi stand for?

A:The number pi represents the ratio of a circle's circumference to its diameter. The ratio never changes for any circle. It is approximately valued at 3.14, but its decimal places have been figured to more than a trillion digits as of 2014.

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Q:
## Where did pi come from?

A:The concept of the mathematical constant pi dates back approximately 4000 years to ancient Mesopotamia. Babylonian mathematicians found that the area of a circle was figured by taking the square of the radius, multiplied by their closest approximation of pi, which was 3.

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