It’s a number an infinitely long number crucial to the lives of mathematicians, physicists and people with bulging bellies. Without it, a circle would be a square, the poetic beauty and mathematical austerity of the twain never meeting would be lost. Yes, it’s Pi that horribly omnipresent irrational number, which is deduced through pure rational logic, beloved to practitioners of math, loathed by those forced to use it and understood by none. It’s long, infinitely long, having one of the shortest names you can imagine, and just to pile the woes on, it’s irrational. The absolute worst news is this last bit: it’s everywhere!!!

### Knock, Knock! Who’s there? Pi! Pi who?

Get a few chips (choose circular ones and avoid the Silicon ones) and sit down with pi. Let’s get to know the apparently harmless beast. Pi is the length of the boundary of a circle, which has unit diameter. Meaning? Draw a circle with a diameter of 1 cm (use a compass please!) and then you can sleep tight with the knowledge that the boundary will be pi cm long. Why? Because a circle is a circle is a circle. Not satisfied? Don’t worry, no one knows.

No, 22^{nd} July is not Pi Day. It’s *approximate* Pi day. Written in day/month format, 22/7 represents a rational approximation to pi. It’s right to the first three digits! A more popular cousin is 14^{th} March. Written in month.day format, 3.14 represents pi. Interestingly, 14^{th} March is also Einstein’s birthday.

Yet, many people aren’t happy! They say that it is not pi, but twice pi that is more fundamental! Let’s called that tau’. Why? The peripheral length can simply be tau x radius, or the area of a circle, simply ½ tau x (diameter)^{2 }. So is there a Tau Day? You bet! It’s 28^{th} June. Write it in month.date format 6.28. This is exactly twice pi correct to the first three digits. While there is no *approximate* tau day, and though that should’ve been a disappointment, tau-ists proudly advertise that their number needs no approximation. It’s not for greenhorns! (Guys, it’s just twice pi!)

### Up close and personal with Pi

Pi is a part of the most beautiful equation ever written.

Look at it with glazed eyes! People familiar with complex numbers (overhyped name!) would point out that the first term (e^{iÏ€}) equals -1. (Take my word for it, or look up a on book on Complex numbers The de Moivre’s Theorem). So in only one equation, you have two most used fundamental constants in Math (e and Ï€) along with the imaginary unit (i), combining to give a really nice real number (-1), which when added to unity (1) gives the omnipresent zero (0). Phew! Overcome with emotions? Please don’t shed tears – it happens to everyone!

However, the greatest utility of pi for the human race is the test of memory! Since pi doesn’t end or even repeat, it has got all braniacs interested and there are international competitions testing one guy’s knowledge of pi with another guy’s. If you’re interested, remember the following rule of thumb: If you remember pi as 22/7, you’re school child. If you know the first three digits(3.14), you’re normal. If you know three more digits after that (3.14159), you’re a physicist. Knowing up to twenty digits (3.1415926535897932385) might brand you as a mathematician or a math freak. If you know a million more (oh, forget it!), you’re a nerd.

Techie-buzz wishes you the very best on your quest to memorize a million digits of pi, Nerd…