The Addiator is a mechanical add/subtract

calculator An electronic calculator is typically a portable electronic device used to perform calculations, ranging from basic arithmetic to complex mathematics. The first solid-state electronic calculator was created in the early 1960s. Pocket-sized ...

, once made by

Addiator Gesellschaft The Addiator is a mechanical add/subtract calculator, once made by Addiator Gesellschaft, Berlin. Variants of it were manufactured from 1920 until 1982. It is composed of sheet-metal sliders inside a metal envelope, manipulated by a stylus, with ...

, Berlin. Variants of it were manufactured from 1920 until 1982. It is composed of sheet-metal sliders inside a metal envelope, manipulated by a stylus, with an innovative carry mechanism, doing ''subtract ten, carry one'' with a simple stylus movement. Some types of Addiators can also handle negative numbers (with a complementary bottom window or by providing a subtraction mode on the back side of the device). Only made obsolete by the electronic variety, it was simple and cheap for the time. It also handles non-decimal measurements, like feet and inches, or pre-decimalization pounds, shillings, and pence. Addition and subtraction require different "screens", handled by turning the instrument over, or flipping a front panel, or, later, by extended sliders and an extra lower panel. Although not always advertised (e.g. the

Magic Brain Calculator Magic or Magick most commonly refers to: * Magic (supernatural), beliefs and actions employed to influence supernatural beings and forces * Ceremonial magic, encompasses a wide variety of rituals of magic * Magical thinking, the belief that unrel ...

mentions "add, subtract, multiply" on its front plate), procedures exist for multiplication (by repeated addition or by individual digit multiplications) and division (e.g. by repeated subtraction, or use of additions combined with

complementary numbers In mathematics and computing, the method of complements is a technique to encode a symmetric range of positive and negative integers in a way that they can use the same algorithm (hardware) for addition throughout the whole range. For a given num ...

). More expensive versions have a built-in slide rule on the back. This type of calculator was introduced by the Frenchman Troncet in 1889. The Addiator was one of the most popular calculators of this sort, and the name is often used to refer to the type generally.

See also

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