So the math already came in handy. I am now the proud owner of a hot pink compass (Thanks, Bib!).
I was trying to figure out how I'd use that to slice up a circle (I have a ruler, and a calculator as well) so I can use the sweet wind projects book my Mom gave me. Turns out you can use the radius of the circle and the compass to mark any number of divisions provided you aren't scared of a little math. :)
So you draw a circle, then make a starting point with your ruler. Let's say you need to divide the circle into three to make a 3 bladed pinwheel. Well you know that the three blades will take up a third of the circle, which means they'll be 120 degrees. Well that's not very helpful since you need a right triangle to use sines and such. But hey! You can draw a triangle between your center point, and two imaginary points at 120 degrees. Then you can slice that in half to form 30-60-90 triangles! :D
Anywho, the short of it is you multiply your radius times the square root of three. That's the distance between your starting point on the circle, and the next third (since I can only measure straight distances with my current tools).
Pinwheels here I come.