Total magnification of objects is 12x.
Dissecting microscopes are microscopes with only one set of lenses so they have less magnification than a compound microscope.
The eyepiece, or ocular lens of microscope, usually has a magnification of 10x. The numbers on magnification knob range from about 0.7 to 3. So, when you want to calculate the total magnification multiply the magnification on the eyepiece with the number on the magnification knob.