Quipu, also called “talking knots”, is a base ten numeric recording device found in the Andean region of South America. Typical quipu construction consists of threads or strings made from llama or alpaca hair or more recently cotton. The devices were used by Incas to collect data and numeric records for taxes, census records, calendars and military organization. Arranged in a base ten configuration, a quipu could contain from a few to as many as 2000 cords.
Archaeologists found quipus were used in Incan culture including the Tahuantinsuyu empire who used the devices for administrative purposes. They were widely used in Andean civilizations from 1450 to 1532 AD and were still in use when the Spanish empire invaded.
How they worked: Quipos consisted of strands arranged in series of 10’s using knots and colors to represent numeric values. Powers of ten are allocated by position on the string in alignment with additional cords. The number 40 then might be represented by four cords with knots in the ten position. Within the 10 position, knots were stranded to correspond to each digit.
Today, the largest collection of quipos is found in Berlin Ethnologisches Museum in Germany. Several museums in Peru also have collections.