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  2. Trachtenberg system - Wikipedia

    en.wikipedia.org/wiki/Trachtenberg_system

    Trachtenberg system. The Trachtenberg system is a system of rapid mental calculation. The system consists of a number of readily memorized operations that allow one to perform arithmetic computations very quickly. It was developed by the Russian engineer Jakow Trachtenberg in order to keep his mind occupied while being in a Nazi concentration ...

  3. Calculator - Wikipedia

    en.wikipedia.org/wiki/Calculator

    A modern scientific calculator with an LCD. 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 devices became available in the 1970s, especially after the ...

  4. Duodecimal - Wikipedia

    en.wikipedia.org/wiki/Duodecimal

    Numeral systems. The duodecimal system, also known as base twelve or dozenal, is a positional numeral system using twelve as its base. In duodecimal, the number twelve is denoted "10", meaning 1 twelve and 0 units; in the decimal system, this number is instead written as "12" meaning 1 ten and 2 units, and the string "10" means ten.

  5. Arithmometer - Wikipedia

    en.wikipedia.org/wiki/Arithmometer

    Arithmometer. The arithmometer ( French: arithmomètre) was the first digital mechanical calculator strong enough and reliable enough to be used daily in an office environment. This calculator could add and subtract two numbers directly and could perform long multiplications and divisions effectively by using a movable accumulator for the result.

  6. Pi - Wikipedia

    en.wikipedia.org/wiki/Pi

    t. e. The number π ( / paɪ /; spelled out as " pi ") is a mathematical constant that is the ratio of a circle 's circumference to its diameter, approximately equal to 3.14159. The number π appears in many formulae across mathematics and physics.

  7. Scientific calculator - Wikipedia

    en.wikipedia.org/wiki/Scientific_calculator

    A scientific calculator is an electronic calculator, either desktop or handheld, designed to perform calculations using basic ( addition, subtraction, multiplication, division) and complex ( trigonometric, hyperbolic, etc.) mathematical operations and functions. They have completely replaced slide rules as well as books of mathematical tables ...

  8. Fold change - Wikipedia

    en.wikipedia.org/wiki/Fold_change

    Fold change. Fold change is a measure describing how much a quantity changes between an original and a subsequent measurement. It is defined as the ratio between the two quantities; for quantities A and B the fold change of B with respect to A is B / A. In other words, a change from 30 to 60 is defined as a fold-change of 2.

  9. Pascal's calculator - Wikipedia

    en.wikipedia.org/wiki/Pascal's_calculator

    Pascal's calculator (also known as the arithmetic machine or Pascaline) 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. [ 2] He designed the machine to add and subtract two numbers ...