### Pi Day Revisited

Yes, today is NOT Pi Day – well, not officially. After all, every day is Pi Day since every day Pi is being used to solve both simple and complex problems, many times without anyone realizing it. Yes, Pi might just have to be the most exciting irrational number on the planet! What do we mean by “irrational” you might ask? Well, think about someone who is not rational – you just can’t pin them down! The same with any irrational number – they are numbers that have infinite decimal expansions (that has no repeating pattern and doesn’t stop). You just can’t tie down an irrational number like pi !

An **irrational number**, then, is any real **number** that cannot be written as a ratio of two integers. This means that an **irrational number** cannot be represented as a simple fraction. Perhaps a better way to think about pi is that it is a number that jumps around a narrow range on the number line. I like to think of numbers like pi as “vibrating numbers” as they move about the closer you look at them, much like a plucked guitar string. When a guitar string is plucked it doesn’t seem to move if you are at a distance away from the musician but, coming closer, you can clearly see the string vibrating. So, irrational numbers reflect what we see in nature. See more here.

After all, pi’s influence extends across time and distance, across cultures and communities; across schools and universities, and across desktops and boardrooms.** Pi **is that silent key on every scientific calculator and it has been seen in some quite unusual places. Did you know that Pi was the symbol used by the **RAF’s 22 squadron**? The Greek sign ‘pi’ denotes the Squadron’s service in France with the 7th Wing, the pilots often taking off over the Wing’s HQ – hence the 22 over 7, or ‘pi’. When the badge was approved by King Edward VIII in May 1936, the Squadron was based in Malta, which accounts for the inclusion of the Cross. The motto “*Preux et audicieux” *means* *Valiant and Brave.

Google’s first share issue, called “Series A” numbered 14,159,256 (the decimal part of pi)! Why? Simple because the Google founders were math majors! Yes, Google was started in 1996 as a research project by Larry Page and Sergey Brin when they were both PhD students at Stanford University in Stanford, California.

Few young mathematicians realize that Albert Einstein’s birthday in on the same day as Pi Day (March 14)!

Did you know that you can** search online **to see if a sequence of numbers (such as your birthday or car number plate) can be found within Pi? Give it a go – it’s kind of fun!