What it is:
An abacus is a counting device that performs basic mathematical functions.
How it works (Example):
The abacus is believed to have been developed in the ancient Near East in the third millennium BCE. An abacus consists of a series of thin parallel bars set into a rectangular frame, usually made of wood. Each bar contains a number of beads that slide along its length. Individuals use the beads as number counters and use the abacus to perform addition, subtraction, multiplication, and division.
Why it Matters:
The abacus has been in continuous use since its conception. It is still widely used in Far Eastern cultures including China and Japan.