How many flat surfaces and edges and vertices?

Answer 1

V= number of vertices

E= number of edges

F= number of faces

For ALL convex polyhedra V-E+F=2

(Euler Characteristic of closed convex polyhera is 2; the genus is 2-2=1)

For a torus (donut shape) V-E+F = 3 (genus is 3-2= 1)