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How did the Inca use quipu to keep records?

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Map showing principal sites of Meso-American civilization, with the Mayan zone of influence shaded in green across southeastern Mexico, Guatemala, Belize, and parts of Honduras and El Salvador. The map highlights major Mayan, Aztec, and other ancient sites, as well as the extent of the Aztec Empire in central Mexico, using color-coded symbols and labels for notable cities and archaeological locations. — Pre-Columbian civilizations Principal sites of Mesoamerican civilization.

The Inca utilized the quipu—an accounting apparatus consisting of a primary textile cord with various pendant and subsidiary cords—to maintain detailed records throughout their bureaucracy.1

How Quipus Functioned

Numeric Encoding: Values were recorded using specific knots tied at varying positions on pendant cords. A figure-8 knot represented 1, a long knot (wrapped 2–9 times) represented 2–9, and simple knots represented powers of 10. A space indicated 0.1
Data Organization: Numbers were read outward from the primary cord, with higher powers of 10 placed closest to it. A single pendant could hold multiple numbers.1
Qualitative Factors: Beyond knots, the meaning of a quipu was influenced by the cord's color, length, composition, ply, and the spacing between cords.1

Administrative Use

Quipus were essential for managing the Inca state, tracking obligations such as labor for the mit’a system, military service, and the distribution of goods. They were maintained by officials at all levels, from the capital of Cuzco to local village headmen. While most known quipus are numeric, some "narrative" quipus may have encoded phonetic information.12