How to balance centrifuge without dummy tubes

A centrifuge is a piece of laboratory equipment commonly used in chemistry and molecular biology. The centrifuge is roughly circular in shape, with circular holes for sample tubes arranged around the perimeter. Balance the centrifuge by positioning sample-filled microtubes and balance tubes opposite one another in the centrifuge rotor. When the centrifuge is balanced properly, the center of gravity for the centrifuge and the test tubes it contains will be located at the center of the centrifuge.