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  2. Pascaline - Wikipedia

    en.wikipedia.org/wiki/Pascal's_calculator

    Pascaline (also known as the arithmetic machine or Pascal's calculator) is a mechanical calculator invented by Blaise Pascal in 1642. Pascal was led to develop a calculator by the laborious arithmetical calculations required by his father's work as the supervisor of taxes in Rouen , France. [ 2 ]

  3. Method of complements - Wikipedia

    en.wikipedia.org/wiki/Method_of_complements

    Pascal's calculator had two sets of result digits, a black set displaying the normal result and a red set displaying the nines' complement of this. A horizontal slat was used to cover up one of these sets, exposing the other. To subtract, the red digits were exposed and set to 0. Then the nines' complement of the minuend was entered.

  4. Mechanical calculator - Wikipedia

    en.wikipedia.org/wiki/Mechanical_calculator

    Mechanical calculator from 1914 An Addiator can be used for addition and subtraction. Two different classes of mechanisms had become established by this time, reciprocating and rotary. The former type of mechanism was operated typically by a limited-travel hand crank; some internal detailed operations took place on the pull, and others on the ...

  5. Stepped reckoner - Wikipedia

    en.wikipedia.org/wiki/Stepped_reckoner

    The stepped reckoner or Leibniz calculator was a mechanical calculator invented by the German mathematician ... add or subtract an 8-digit number to/from a 16-digit ...

  6. Curta - Wikipedia

    en.wikipedia.org/wiki/Curta

    The nines' complement math breakthrough eliminated the significant mechanical complexity created when "borrowing" during subtraction. This drum was the key to miniaturizing the Curta. His work on the pocket calculator stopped in 1938 when the Nazis forced him and his company to concentrate on manufacturing precision instruments for the German ...

  7. Comptometer - Wikipedia

    en.wikipedia.org/wiki/Comptometer

    The Comptometer was the first commercially successful key-driven mechanical calculator, patented in the United States by Dorr Felt in 1887.. A key-driven calculator is extremely fast because each key adds or subtracts its value to the accumulator as soon as it is pressed and a skilled operator can enter all of the digits of a number simultaneously, using as many fingers as required, making ...

  8. Adding machine - Wikipedia

    en.wikipedia.org/wiki/Adding_machine

    Subtraction was impossible, except by adding the complement of a number (for instance, subtract 2.50 by adding 9,997.50). Multiplication was a simple process of keying in the numbers one or more columns to the left and repeating the "addition" process. For example, to multiply 34.72 by 102, key in 3472, pull crank, repeat once more. Wheels show ...

  9. Slide calculator - Wikipedia

    en.wikipedia.org/wiki/Slide_calculator

    A slide calculator, also known as an Addiator after the best-known brand, is a mechanical calculator capable of addition and subtraction, once made by Addiator Gesellschaft of Berlin, Germany. Variants of it were manufactured from 1920 until 1982. The devices were made obsolete by the electronic calculator.

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