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## Happy Pi Day

Pi or π is most commonly rounded to 3.14, making March 14 the happy occasion of Pi Day. Here are some facts about this mysterious and irrational number:

- Pi is the ratio of a circle’s circumference (measurement around the edge) and its diameter (measurement straight across).
- The symbol, π, is the Greek letter for ‘P’.
- As an ‘irrational number’, the digits of Pi are infinite and don’t fall into a repetitive digit.
- Pi as a concept was known by the ancient Babylonian’s nearly 4,000 years ago, as it is recorded on tablet from as early as 1900 BC.
- Pi is now even used when commanding rovers on Mars as a value to covert between degrees and radians.
- Google employee Emma Haruka Iwao has marked the occasion by breaking the Guinness world record for calculating the most accurate value of Pi to a staggering 31.4 trillion decimal places.
- The record for the most digits of pi memorized belongs to Rajveer Meena of Vellore, India, who recited 70,000 decimal places of pi on March 21, 2015, according to Guinness World Records. How many decimal places can you memorise?

3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067…

### Read more:

NASA’s annual Pi Day Challenge: Pi in the Sky

18 ways NASA uses Pi

35 Surprising Facts About Pi

Scientific American: What is Pi and how did it originate?

Live Science: 10 Surprising Facts About Pi

Search the first 200 million digits of Pi

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