Pi Approximation Day – History and Significance

Pi Approximation is a day devoted to mathematical constant pi (π). This constant is used in various formulas in both mathematics and physics. This constant is defined as the ratio of a circle’s circumference to its diameter. Pi approximation day is celebrated every year on July 22. Wonder why? Because this constant is equal to 22/7. There is another day dedicated called Pi day celebrated every year on March 14 because pi is approximately equal to 3.14. Smart isn’t it? This day is also called Casual Pi day!

History of Pi and its Significance

Pi has been an integral part of the mathematics world for at least 4000 years. Ancient Babylonians first discovered that by squaring a radius of a circle three times, the area of the circle could be calculated. This approximated the value of Pi as 3. Babylonians came very close to the value of the first 3 decimals of Pi. A Babylonian tablet from the 17th century BC was the
first-ever recorded approximation of Pi and had the value of Pi as 3.125.

Ancient Egyptians also tried to calculate the area of a circle using pi. They estimated the value of Pi as 3.1605. To come up with this number they used a formula to find the area of a circle. Another great mathematician Archimedes of Syracuse tried to find the value of pi. He used the Pythagorean Theorem in 250 BC. He approximated the value of pi between 3 1/7 which is equal to 3.1428 and 3 10/71 which is equal to 3.1408.
Many civilizations such as Indians, Arab and Chinese had mathematicians who figured out Pi till the ninth decimal digit. However, Archimedes’s methods were lost in history. Then in the 5th century, A Chinese astronomer, inventor and mathematician, Zu Chongzhi used a long and complex set of calculations to calculate Pi. He created a record that was not surpassed for 800 years and estimated the value of pi between 3.1415926 and 3.1415927. By 1630 Austrian astronomer Christoph Grienberger calculated 38 digits of pi European mathematicians like Leibniz and Gregory popularized the use of pi but the symbol of the pi constant was introduced by a welsh mathematician, William Jones in 1706 the use of Greek letter π for Pi. It was popularized by famous mathematician Leonard Euler in 1737. 527 digits of Pi were calculated by the end of the 19th century. 2037 digits of pi were calculated when an ENIAC computer was used and became the first machine to calculate pi and 16 years later the number went up to a million because of technological advancements.
Now the world record is at 31 trillion digits of Pi calculated by Google employee, Emma Haruka Iwao. It is an essential part of astronomy with NASA using 15 digits of Pi for space missions and 40 digits of Pi to calculate the circumference of the visible universe, Pi helps calculate these to a high degree of accuracy. Now Pi is used as a test for a computer’s abilities as a stress test.


Pi Approximation Day and Pi day are most importantly a celebration of Mathematics and Mathematicians worldwide and many celebrate it by holding pi remembering competitions and eating pie.

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