###### By Anupum Pant

### “International” Pi day?

Today is pi day. Pi day is celebrated on March 14 at the Exploratorium in San Francisco (March 14 is 3/14) at 1:59 PST which is 3.14159.

Since pi day is today’s date written in the mm.dd (03.14) format, it could not be a pi day for most of you because dd.mm is the format used for writing dates in most countries around the world. In fact, those countries where more than half of the world’s population resides, will never have a pi day because you know, we can’t have a 14^{th} month! Pi day is a valid celebration for people living only in the United States (including the 49^{th} and northernmost state, Alaska and Hawaii of course) and Belize. Everywhere else people get zilch today?

Firstly, there is always the **pi approximation day**, which is celebrated on 22nd July (22/7) and uses the dd.mm format. Talking about March 14th, there is much more to pi day than just the date format itself. Let’s see…

### Birthdays

I know,** Eugene Cernan** – The NASA astronaut who was the last man on the moon, and the one you can hear **speaking in a popular Daft Punk Track** – is one famous man who was born on pi day, 79 years from now, is an American too.

But guess what? Albert Einstein, one of the most genius men of recent times, was born on pi day too. He was a German born physicist (He did live in the US for more than 15 years and in fact, even took his last breath in New Jersey)

So, you see there is a little bit of pi day for every one around the world today. It is not just an American thing. Now moving on the most amazing things about pi.

### Irrational pi

Firstly, pi, unlike what we all are taught in school, isn’t 22/7. 22 divided by 7 is just an approximation of pi – it is only 99.95975% accurate. As we all know, pi is actually the ratio of a circle’s circumference to its diameter. A slightly better approximation of pi would be 104348/33215 – which is 99.99999998944% accurate. But, since it is an irrational number, it can never be written in the form of a fraction.

### Exact Value

The exact value of pi is impossible to write in digits because the number of digits needed to write it would be *infinite* and could never be fit inside the known universe.

To think of it in another way, if you divided the whole universe into the smallest possible volumes (plank volume), you’d end up with a mind bogglingly large number of volumes. Suppose you started writing the digits of pi inside these little volumes, you’d finish up the universe and would be still left with infinite more digits to write.

### The Digits of Pi

The latest record for the maximum number of known digits of pi is **12.1 Trillion digits (December 28, 2013)**, as calculated by Alexander J. Yee & Shigeru Kondo. They have run out of disk space to store more numbers. Here you can have a look at the first 100,000 digits of pi. And One million digits, if you need more than that.

In these first one million digits, the sequence 12345 occurs 8 times!

**The Feynman Point:** If you’d like to hear what pie would sound like if you mapped a couple of pleasant sounding notes to each of the digits of pi, try listening to this. If you kept listening for a while and made it till the **762th digit**, you’d hear a series of (6 of them) high frequency notes (the ones mapped to the digit nine) that get played continuously. This place in the digits of pi is called the Feynman point where six 9s occur one after another. Isn’t it incredible for six same numbers to be there consecutively in a random irrational number!

### Practically useful pi

Pi can be used in real life to make a couple of things easier. For instance, if you were to find the **size of your hat** (usually measured in diameters), you’d have a hard time measuring the diameter of your head. This is what you can do to get a good approximation:

Measure the circumference of your head and divide it by π.

**Another one trick is used by forest guards:** To estimate the height of an elephant the Diameter of an elephant’s foot is multiplied by 2 π.

### Pi Jokes, facts and Coincidences

- It is an impressive coincidence that 3.14 if horizontally flipped, looks like the word “Pie”. You can check this in the mirror.

- Another one is that, the 16th Greek letter is ‘Pi’ and the 16th letter in the English alphabet is ‘P’.
- The famous comedian John Evans once made a joke: “What do you get if you divide the circumference of a jack-o’-lantern by its diameter? Pumpkin π.

- There is a cologne named pi and is sold with the following marketing mantra: “highlighting the sexual appeal of intelligent and visionary men.”
- The height of the Great Pyramid of Giza multiplied by 2 π is equal to the perimeter of its base.
- The 90841th place in pi is 122189 – which is also my birth date in the mmddyy format.
**Find yours here**and tell me in the comments below.

Download the **PiDay wallpaper here**.

**Do share with me in the comments, other facts about pi you know and I haven’t covered them here.**

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