Stepped reckoner

... it is beneath the dignity of excellent men to waste their time in calculation when any peasant could do the work just as accurately with the aid of a machine.

[4][5] Two prototypes were built; today only one survives in the National Library of Lower Saxony (Niedersächsische Landesbibliothek) in Hanover, Germany.

The machine is about 67 cm (26 inches) long, made of polished brass and steel, mounted in an oak case.

Sequences of these operations can be performed on the number in the accumulator; for example, it can calculate roots by a series of divisions and additions.

In a letter of 26 March 1673 to Johann Friedrich, where he mentioned the presentation in London, Leibniz described the purpose of the "arithmetic machine" as making calculations "leicht, geschwind, gewiß" [sic], i.e. easy, fast, and reliable.

Leibniz also added that theoretically the numbers calculated might be as large as desired, if the size of the machine was adjusted; quote: "eine zahl von einer ganzen Reihe Ziphern, sie sey so lang sie wolle (nach proportion der größe der Machine)" [sic].

From 1894 to 1896 Artur Burkhardt, founder of a major German calculator company restored it, and it has been kept at the Gottfried Wilhelm Leibniz Library ever since.

Repeated subtractions are done similarly except the multiplier dial turns in the opposite direction, so a second set of digits, in red, are used.

To divide by a multidigit divisor, this process is used: It can be seen that these procedures are just mechanized versions of long division and multiplication.