Commonly when we are trying to obtain the total magnification of a microscope we need two measures, eyepiece power, and objective lenses power, to obtain the total magnification we only need to multiply the magnification of both lenses, now commonly optical microscopes reach 100x sometimes 200x, going further cause severe optical distortion, so we assume that this is a purely hypothetical case, as magnification over 600 must be approached with another type of microscope. So the total magnification would be as follows:
675 x 25 = 16 875x