Iron balls from a sphere

Volume of sphere $V = \frac{4}{3}\pi R^3 = \frac{4}{3}\pi (8)^3 = \frac{4}{3}\pi (512)$. Volume of each iron ball $v = \frac{4}{3}\pi r^3 = \frac{4}{3}\pi (1)^3 = \frac{4}{3}\pi$. Number of balls $n = \frac{V}{v} = \frac{512}{1} = 512$.