M.3—Magnification, actual size and geometry

Magnification = image size ÷ actual size; use the same units before calculating and apply the relevant area, perimeter or volume formula.

Check whether the question asks for a length, area or volume because scaling powers differ.

A 20 µm cell shown as 40 mm long has magnification 2000× after converting 40 mm to 40 000 µm.

Do not divide by magnification without first matching units.