What is the magnification of a microscope using the 40x objective?

The magnification of a microscope using the 40x objective is 40 times the actual size of the specimen being observed. To determine the total magnification, you must also consider the eyepiece (ocular lens) magnification, which is typically 10x. Therefore, if using a 40x objective with a 10x eyepiece, the total magnification would be 400x.