The yupana is a device used by the Incas, presumably as a type of calculator

Calculator

An electronic calculator is a small, portable, usually inexpensive electronic device used to perform the basic operations of arithmetic. Modern calculators are more portable than most computers, though most PDAs are comparable in size to handheld calculators.The first solid-state electronic...

. Though some researchers have hypothesized how this implement might function like an abacus

Abacus

The abacus, also called a counting frame, is a calculating tool used primarily in parts of Asia for performing arithmetic processes. Today, abaci are often constructed as a bamboo frame with beads sliding on wires, but originally they were beans or stones moved in grooves in sand or on tablets of...

, others are less certain that it was used for this purpose. The 16th-century account of Spanish priest José de Acosta

José de Acosta

José de Acosta was a Spanish 16th-century Jesuit missionary and naturalist in Latin America.-Life:...

 suggests that Incas may have possessed such a device:
Researchers believe that such calculators were based on Fibonacci number

Fibonacci number

In mathematics, the Fibonacci numbers are the numbers in the following integer sequence:0,\;1,\;1,\;2,\;3,\;5,\;8,\;13,\;21,\;34,\;55,\;89,\;144,\; \ldots\; ....

s to minimize the number of necessary grains per field.