Quipu n. : A contrivance employed by the ancient Peruvians, Mexicans, etc., as a substitute for writing and figures, consisting of a main cord, from which hung at certain distances smaller cords of various colors, each having a special meaning, as silver, gold, corn, soldiers. etc. Single, double, and triple knots were tied in the smaller cords, representing definite numbers. It was chiefly used for arithmetical purposes, and to register important facts and events.

Example:
How did the Inca's Quipu serve their needs for record-keeping?

Taxonomy
quipus, knots, Inca quipu, cords, Inca, Khipu, Quipucamayocs, knotted cords, strings, Conservation, digit, Frank Salomon, Ascher, Ordish, Rapaz, damage, New York, eight knots.

Defination from the web:
Quipu or khipu (sometimes called talking knots) were recording devices used in the Inca Empire and its predecessor societies in the Andean region. A quipu usually consisted of colored spun and plied thread or strings from llama or alpaca hair. ...