Abacus
The abacus is one of the oldest counting devices used by humans. It consists of a wooden frame with rods or wires on which beads are moved back and forth to perform arithmetic calculations. The abacus is a simple and efficient tool for addition, subtraction, multiplication, and division. It is widely used in many Asian countries and is still used today by some people for quick calculations.

Pascaline
The Pascaline was one of the first mechanical calculators invented by Blaise Pascal in the 17th century. It was designed to help with arithmetic calculations and could perform addition and subtraction. The Pascaline had a series of gears and dials that allowed users to input numbers and perform calculations by turning the dials. It was a significant advancement in the field of computing and laid the foundation for future mechanical calculators.

Tabulating Machine
The tabulating machine was an early form of mechanical calculator developed by Herman Hollerith in the late 19th century. It was used to process data by reading information from punched cards and tabulating the results. The tabulating machine was primarily used for census data and helped revolutionize the way information was processed and analyzed. It was a precursor to modern computers and played a crucial role in the development of data processing technologies.