The aorta carries blood away from the heart and eventually branches into a large number of capillaries that distribute the blood to various body organs. If for an average person, the aorta has a radius of 1.2 cm and blood travels through it at a speed of 42 cm/s and the capillaries have an average radius of 5.0 10-4 cm and blood travels through them at a speed of 0.005 cm/s, determine the approximate number of capillaries in the human body.