The Inca were able to make very precise calculations in astronomy, engineering and mathematics due to their use of <em>quipu</em>. A <em>quipu</em> is a recoding device made out of strings and used by a number of cultures in the Andean area. It consists of a number of strings that are tied into knots in a particular symbolic pattern. <em>Quipu</em> were also used to collect data, maintain records, collect census records and other types of organizational tasks.
