Did you know? Abacus

The abacus is a simple counting machine first used by the ancient Greeks and Romans.  It consists
of rows of beads strung on wires:  those on the first wire count as ones, those on the second wire count as tens, and on the third they count as hundreds, and so on. 

The abacus is still used in Eastern countries such as China and Japan.  The Romans sometimes used small stones as counters.  They called these counters calculi, and it is from this that we get our word calcuate.