Is it possible to divide a circle into $7$ equal "pizza slices" (using geometrical methods)? Or is it possible to divide a circle into n equal "pizza slices" (I don't know how to call these parts, but I think you'll know what I mean), where n hasn't got a common divider with $360$? Or are the $360$ degrees just "arbitrarily" chosen, in such way that it's also possible to make a system with $7$ "degrees" in a circle?
The main question is actually if it's possible with a ruler and a pair of compasses to divide a circle into any number of slices, and if there's a condition for a number (e.g. a common divider with $360$ as I suggested) so it's possible to slice the circle in such a number of pieces.

You're looking for constructible angles; see this link:http://en.wikipedia.org/wiki/Compass-and-straightedge_construction
The only numbers of pizza slices you can create are powers of two times distinct Fermat primes (so 8 times 3 times 17 would work).
