This 14th day of march, 3.14, makes it pi day. π is a very special number mathematics and trigonometry.
Circumference of a circle is a function of π times twice the radius:
C(r) = 2πr
What's cool about this, is that the concept of radian measures come from this, where 360°≡ 2π (is equivalent to) on a unit circle. Degrees are units that basically come from nowhere, I mean who's to say that a full circle has to be 360 degrees? Radian measures are actual measured numbers, making them more usable within equations.
e^(π*i) = -1
My friend showed me this last one, I thought it was cool.
Today is the day you can be mathematically irrational. (and eat pi*e)