Abacus

An Abacus is a calculating tool that historically has been used to perform arithmetic operations. It is still in use today in some places. Typically an abacus consists of a frame with beads on wires. depending on the type of abacus each wire might have 10 beads or 5 beads separated from another 2 beads.

Stamps

Stamp Description
Cuba, 13c, 1970
Scott: 1570 A415
Congo, 2.50k, 1971
Scott: 748 A142
Colombia, 3p, 1977
Scott: 861 A382
Germany, 80pf, 1987
Scott: 1499 A607