March 14 is Pi Day, in case you didn’t know. So, here’s a little slice of that most infamous of irrational numbers.

The number pi, represented by the Greek letter, pi, is rather puzzling. As far as significant figures go, it’s got as many as you could ask for, being an irrational number it simply goes on forever. 3.1415926535897932384626433832795…

All that hooey about 22 divided by 7 is simply wrong. 22 divided by 7 is out after the third decimal place.

Anyway, what is pi. It’s the ratio of the circumference of a circle to its diameter, that’s what it is. But if that simple statement still leaves you none the wiser, then take a look at this neat little animation courtesy of Wikipedia and brought to my attention by fellow science blogger eKstreme over on blogsci.com.

As you can see, to roll a circle one full turn along a number line takes you a distance pi from you starting point till the starting point on the circle touches the line again. Now, imagine trying to measure that distance as accurately as possible…you could always add another significant figure if you use a more accurate rule. In fact you could go on forever… It’s not quite a mathematical proof of the irrationality of pi, but you get the idea.

Meanwhile, Angsuman Chakraborty on the Simple Thoughts blog has a neat bit of Java code that can be used to generate pi to a specific number of significant figures, with arbitrary precision in other words. Useful if you need to calculate the area of that circle to 856,965 decimal places.

Don’t take a slice of my pi!