A 10-key adding machine is a mechanical calculator used in companies and stores before there were electronic calculators. This machine can perform simple calculations, such as addition and subtraction of numbers. The earliest adding machine dates back to the 1800s.
The 10-key adding machine is also referred to as a printing machine because it can total up a long list of numbers and then print out the results of the calculation. The adding machine consists of the numbers 0 through 9 and the mathematical function keys for addition and subtraction. There also are other keys, such as the "T" key for total and the asterisk.
Depending on the specific type or brand of adding machine, there may be other keys or ways to perform division and multiplication calculations. For example, the Imperial Office Master machine, which was used during the early 1970s, could add and subtract. However, there were special techniques used to perform division and multiplication calculations.