The sphere needs just one measurement — its radius: $V = \tfrac{4}{3}\pi r^3$ — read aloud: V equals four-thirds pi r cubed. Its skin is just as tidy: $S = 4\pi r^2$ — S equals four pi r squared — exactly four circles' worth of area, a fact lovely enough that Archimedes asked for it on his tombstone.

Notice who wears which power: the VOLUME cubes the radius, the SURFACE squares it. And cubes grow ferociously — double the radius and the volume jumps ×8; triple it and you're at ×27. So estimate before you compute. A five-second guess of “a few hundred” is the net that catches a beach ball the size of a gymnasium.