Counting with Knots: The Inca Quipu
The Inca people ruled a huge empire high in the Andes Mountains of South America. They kept careful records, but they did not use writing like ours. Instead, they used a tool called a quipu, which is pronounced KEE-poo.
A quipu was a set of strings tied to one thick cord. Each string had knots in it. The place of a knot on the string, and the kind of knot, stood for a number. The strings came in many colors, and the colors may have shown what was being counted.
Special record keepers learned how to make and read quipus. They could count things such as bags of corn, llamas in a herd, or people living in a village. The records helped the empire know what it had stored and who could be called on to work.
Quipus were made of cotton or wool, so they could be rolled up and carried by runners along mountain roads.
Experts today understand how the quipu showed numbers. But they are still trying to learn if some of the strings held other kinds of messages.