You've probably heard about me from your math teachers or whatsoever.
I am a mathematical constant, the ratio of a circle's circumference to its diameter, commonly approximated as 3.14159. I've been represented by the Greek letter "π" since the mid-18th century, though I've also sometimes spelt out as "pi".
Many ancient civilizations knew about me, but they could not find my exact value. Neither could humans today. William Jones was the first to use the π symbol to represent the concept.
I'm celebrated on March 14 every year. People usually eat pie on that day. It is an official holiday in the United States. My holiday is formally known as Pi Day.
Ancient civilizations knew that there was a fixed ratio of circumference to diameter that was approximately equal to three. The Greeks refined the process and Archimedes is credited with the first theoretical calculation of Pi. Pi was proven to be irrational in 1761.
• Pi is the most recognized mathematical constant in the world.
• The symbol for pi (π) has been used regularly in its mathematical sense only for the past 250 years.
• Computing pi is a stress test for a computer - a kind of "digital cardiogram."
13,300,000,000,000 (13.3 trillion) digits have been computed by October 8, 2014. It took houkouonchi, the person behind it, 208 days to compute.
Akira Haraguchi, a retired Japanese engineer, holds the unofficial world record for memorizing the most digits of pi. He claims to have reached 100,000th digit in just a day.