The size of Betelgeuse is variable (it pulsates); plus, thereare different estimates. But its diameter is approximately 900times that of our Sun, which in turn is roughly 100 times thediameter of Earth (actually 109, but the data don't justify a veryexact calculation), so Betelgeuse has roughly 900 x 100 = 90,000times the DIAMETER of Earth; the ratio of volumes is that samenumber, cubed, or (after some rounding) about 700,000,000,000,000times as much.