comptometer

The comptometer was an early mechanical calculator that performed addition, subtraction, multiplication, and division. Invented by American inventor Alphonse D. Bell in the 1880s, it was the first commercially successful key-driven calculator. Unlike earlier machines that relied on cranks or levers, the comptometer used a keyboard with ten keys per digit, arranged in columns. Pressing a key entered a digit, and the sum or result was displayed mechanically.

Comptometers were widely used in businesses and government offices from the late 19th century until the mid-20th century. Their speed and efficiency made them indispensable for tasks such as accounting, payroll, and inventory management. While powerful for their time, they were complex to operate and required specialized training. Operators, often called "computers" due to their role in performing calculations, needed to develop a rapid and accurate touch for the keyboard.

The introduction of electronic calculators and later digital computers rendered the comptometer obsolete. However, its invention marked a significant step in the evolution of computing, paving the way for the automated calculation devices that are commonplace today. The design principles of the comptometer influenced later mechanical and early electronic calculators.