To determine the power or magnification of a microscope, you need to multiply the magnification power of the objective lens by the magnification power of the eyepiece lens.

Here's the formula:

Microscope Power (Magnification) = Objective Lens Magnification × Eyepiece Lens Magnification

Let's use an example to illustrate:

If the objective lens has a magnification of 40x (denoted as "40x") and the eyepiece lens has a magnification of 10x (denoted as "10x"), then the total microscope magnification would be:

Microscope Power = 40x × 10x = 400x

This means that the microscope provides a magnification of 400 times the original size of the specimen being viewed.

It's important to note that some microscopes may have multiple objective lenses with different magnification powers, allowing you to change the level of magnification depending on your needs and the specimen you're observing.