Happy Pi Day! Today is the day we honour the ridiculously irrational number that is pi π, which looks like a tiny chair. It is basically the ratio of the circumference of a circle to its diameter. Why we call it an irrational number is because it cannot be written as a simple fraction, and instead, it can be expressed as an infinite, nonrepeating decimal (3.14259…) or approximated as the fraction 22/7. And if you want to make this day nerdy-er, you can also celebrate Albert Einstein’s birthday!
1. The ancient Babylonians and Egyptians knew of pi’s existence nearly 4,000 years ago
In Babylon, a clay tablet dated 1900-1600 BC has a geometrical statement that calculates pi as 3.125. In Egypt, the Rhind Papyrus (a famous Egyptian mathematical document) dated around 1650 BC has a formula for the area of a circle that lists pie’s value as 3.1605.
2. Do you speak ‘Pi’?
Literary nerds invented a dialect known as Pilish where the numbers of letters in successive words match the digits of pi. For example, Mike Keith wrote the book “Not a Wake” entirely in Pilish:
Now I fall, a tired suburbian in liquid under the trees,
Drifting alongside forests simmering red in the twilight over Europe.
“Now” has 3 letters, “I” has 1 letter, “fall” has 4 letters, and so on… Yeah yeah… it’s not really a new ‘language’, but it does feel like a type of poem.
3. There are many ways to remember Pi
Number enthusiasts have memorised many digits of pi. How? Well they use a bunch of methods, but mainly they use mnemonic techniques known as piphilogy to help them remember. Usually, they use poems written in Pilish! Chao Lu, from China, recited pi from memory to 67,890 places in 2005, according to The Guinness World Records. However, on March 21 2015, the record for the most digits of pi memorised belongs to Raiveer Meena of Vellore, India, who recited 70,000 decimal places of pi. However, unofficially, Akira Haraguchi videotaped a performance of his recitation of 100,000 decimal places of pi in 2005 and more recently topped 117,000 decimal places.
4. Pi-ramid at Giza
A publisher and writer, John Taylor, first proposed the idea that Egypt’s Great Pyramid at Giza, built around 2589 to 2566 BC was designed based on pi. Taylor found that dividing the perimeter of the pyramid of its base by its height produces a number that is close to 2*pi. Others have since made the link between the Great Pyramids and pi as well but it may not have been intentional.
5. Computing pi
It’s actually easy to calculate pi by measuring the circumference or the distance around the edge of a circular or curved object, and the diameter of several circles and computing the slope (circumference divided by diameter). Computers can even get more accurate measurements. As of December 2013, it was found that computers calculated pi to a record 12 trillion digits.
6. You can hand-calculate pi
If you’re hoping to calculate pi yourself, you can use an old-fashion technique that will require using a ruler, a can, and a piece of string, or a protractor and a pencil. The downside of this method, however, is that it requires a can that is actually round whilst the accuracy is limited by how well a person can look string around its circumference. You can also draw a circle with a protractor and then measuring its diameter or radius with a ruler involved a fair amount of dexterity and precision.
If you want a more precise option, you can use geometry; break up a circle into multiple segments (like pizza) and then calculate the length of a straight line that would turn the slice into an isosceles triangle, which has 2 sides of equal length. Now add up all the sides and you’ll get a rough approximation for pi. The more slices you create, the more accurate the approximation of pi will be. And if you want to add more fun, use an actual pi. Jk.
7. Pi sounds divine
Just like pie. 18th century mathematician Johann Heinrich Lamber proved pi’s irrationality by expressing the tangent of x using a continued fraction. Later on, mathematicians showed that pi was also transcendental; meaning the numbers can’t be the solution to any polynomial that has rational number coefficients a.k.a there’s no finite, root-finding formula that can be used to calculate pi using rational numbers.
While many mathletes are enamoured with pi, there’s also a resistance movement growing as some argue pi is a derived quantity and that the value tau (equal to twice pi) is a more intuitive irrational number. Tau directly relates the circumference to the radius which is a more mathematically consequential value, according to Michael Hartl (author of the “Tau Manifesto”). Tau also works better in trigonometric calculations, so that tau/4 radians corresponds to an angle that sweeps a quarter of a circle, for instance.
Understood nothing? It’s okay! You can still be a fan of Pi! Just get order some pie with some of your buddies today and celebrate this ridiculous math thing we used in highschool to calculate things from round things.
