The upper bead represents 5 and the lower bead represents 1. The abacus is a simple calculation tool invented by the working people in ancient China. The beads on the abacus represent different numbers. One bead on the abacus represents five times the number of one bead on the bottom. So one bead on the abacus represents 5, and one bead on the abacus represents 1. Advantages of the abacus: It is easy to calculate. The abacus requires the close cooperation of the brain, eyes and hands. It is a good way to exercise the brain; it is low cost, green and environmentally friendly, etc.