An abacus is an ancient tool used for counting and making mathematical calculations. This abacus is modeled after a traditional Chinese version called a suanpan or counting tray. These tools are still widely used in business in Asia and Africa, however, in the United States, the abacus has largely been replaced by calculators and computers.
To count with an abacus you first move a bead up to the top of its section to count it. From right to left, the beads in the bottom section count as 1 in the first stack, 10 in the second stack, 100 in the third stack, etc. The beads in the top section count as 5 in the first stack, 50 in the second stack, 500 in the third stack, etc.