# There’s a Pi Day?

Yes, title, indeed there is a Pi day, and unless I’m mistaken it’s also today. Pi is a pretty interesting number that’s worth going over in a post so I thought I’d flesh the idea out a little here. So go grab 3.1415926… slices of pie and I’ll get you up to speed on a number that’s both irrational and ubiquitous (it’s a bit like UFO and ghost sightings in that respect, although you can’t often use ghosts to work out the area of a circle).

Now, when I was in school I learned a cringe-inducing song that had to be sung in the voice of a farmer from the west country. For you non-Brits that’s the counties in the South-West that have a very distinctive accent and make fantastic pasties and ice creams (although you usually wouldn’t have them together). It taught me that the circumference of a circle was pi x diameter, and that the area of a circle is pi x the radius squared. Obviously these simple mathematical formulas are incredibly useful in geometry and working out dimensions of shapes, which leads into not only mainstream mathematics but engineering and cosmology, and other awesome sciences.

It has been suggested however, that pi should be replaced by the proposed number tau, which is simply pi x 2. It isn’t much more useful as a number, as you can see by how simply it is explained, but it would switch over those two formulas a little, so we’re dealing with calculations centering around radii rather than diameters, because really, screw diameters.

Nevertheless pi is both awesome, iconic and half tau. But one of the most interesting things about it is its status as the most famous irrational number. As an irrational number, pi never ends (in the same way a numberline never finishes, its digits go on forever, no matter how far you look), but more than that, it has no repeating sequences. In this way, pi’s sequence has no pattern, and must be figured out by finding a more precise figure for this mathematical constant. The short definition of an irrational number is any number that cannot be expressed as a ratio a/b (using whole numbers, or integers as a and b), such as 1/2. 3/4 and so on, with whole numbers being 5/5 and 7/7. It is impossible to write pi out like this, though it is a ‘real number’ (has a space on a continuous numberline).

Even more interesting is that pi is distinct among even rational numbers, being a transcendental number (not a root of a non-zero rational number/equation). While other irrational numbers can be found in square roots, such as the square root of two, well, you can see where I’m going with this, it’s pretty special.

For those of you still hungry for more pi facts, watch Scishow’s celebration of pi day below.