You can divide the two values A = diameter of bacterium B = diameter of virus A/B = (10^(-6))/(10^(-7)) A/B = 10^(-6-(-7)) A/B = 10^(-6+7) A/B = 10^(1) A/B = 10 Since the ratio of the two diameters is 10, this means that the diameter of the bacterium is 10 times greater than that of the virus.
