Volume formed by rotating square by 360 deg If I know the area of the square and I rotate it around one of the edges by $360$ deg, it forms a solid cylinder. Why then is the volume of this cylinder not equal to "area of the Square" multiplied by $360$? Or is it "area of the Square" multiplied by circumference multiplied by diameter?
Hints: Volume of the cylinder is the area of the (circular) base times the height.

As you rotate your square, what determines the area of the base; and what determines the height?
Imagine a cylinder with height $h$ and radius $r$. By definition, the formula for the volume of a cylinder is $$V= \pi r^2 h $$ Notice that the formula has nothing to do with "multiplying by $360^\circ$". The formula should make intuitive sense. The $\pi r^2$ that appears in $V$ is the cross-sectional area of the cylinder, so multiplying that quantity by $h$ will "stretch" that cross-section into the $3$-d volume we recognize as a cylinder. 

Now imagine a square $S$ with base and height of length $s$. If you rotate $S$ by $360^\circ$ about one of its edges, then you will indeed generate a cylinder. Convince yourself that $h=s$ and $r=s$. Hence the volume of this cylinder must be $$V_S = \pi(s^2)s = \pi s^3$$