# May I have a large container of coffee

Mar 2015
Tomorrow (March 14) is Pi Day, an annual celebration of the mathematical constant "p". Although many of us are aware of Pi, and know that Pi is 3.1415926 (remembered with the mnemonic "May I have a large container of coffee"), how much do we know about this number?

• Pi is the relationship between the perimeter of a circle (the circumference) and the distance across that circle (the diameter), among a multitude of other applications in maths, physics, and engineering.

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• Pi Day has been celebrated since 1988 (where it was marked with apple pie)!

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• This year is a very special Pi Day because it takes place on 3.14.15 (in the American way of writing the date), and at 9:26:53 the time will correspond with the first ten digits of pi (3.141592653).

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• Pi has been known for almost 4,000 years! The ancient Babylonians calculated the area of a circle by taking three times the square of its radius, which gave a value of pi = 3. One Babylonian tablet (ca. 1900-1680 BC) indicates a value of 3.125 for pi, which is a closer approximation.

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• The first calculation was done by Archimedes, one of the greatest mathematicians of ancient times, who lived between 287-212 BC. He calculated the area of a circle using the Pythagorean Theorem. He approximated the value of pi as between 3 1/7 and 3 10/71.

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• A couple of hundred years later, Chinese mathematician Zu Chongzhi calculated the value of the ratio of the circumference of a circle to its diameter to be 355/113.

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• The Greek letter p didn't arrive until 1700s.

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• The value of pi has been calculated to more than two trillion decimal places.

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• Chao Lu of China set the world record in 2005 for memorising the value of pi. He recited from memory the first 67,890 digits, taking him 24 hours and four seconds at a rate of 47 digits a minute (he didn't even pause for food)!

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• Pi day is also Albert Einstein's birthday.

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• If you write the numbers 3.14 on a piece of paper and hold it to a mirror it looks like 'PIE'.

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Happy Pi Day everyone!