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  2. Abacus - Wikipedia

    en.wikipedia.org/wiki/Abacus

    In the left part were four beads. Beads in the first row have unitary values (1, 2, 3, and 4), and on the right side, three beads had values of 5, 10, and 15, respectively. In order to know the value of the respective beads of the upper rows, it is enough to multiply by 20 (by each row), the value of the corresponding count in the first row.

  3. Roman abacus - Wikipedia

    en.wikipedia.org/wiki/Roman_abacus

    However, he stated specifically in the penultimate sentence of section 32 on page 23, the two beads in the bottom slot each have a value of 1 / 72. This would allow this slot to represent only 1 / 72 (i.e. 1 / 6 × 1 / 12 with one bead) or 1 / 36 (i.e. 2 / 6 × 1 / 12 = 1 / 3 × 1 / 12 with two beads) of an uncia respectively.

  4. Programma 101 - Wikipedia

    en.wikipedia.org/wiki/Programma_101

    Olivetti, Programma 101 General Reference Manual, hosted by the Old Calculator Web Museum, retrieved 2009-12-17. Internal pictures Old Calculator Web Museum. A simulator of the Olivetti Programma 101 "General Reference Manual". Old Calculator Museum. A Technical Description of the Olivetti Programma 101 with a picture gallery, by Alfredo Logioia

  5. Pier Giorgio Perotto - Wikipedia

    en.wikipedia.org/wiki/Pier_Giorgio_Perotto

    The innovative calculator, also known as Perottina, named after its inventor, was one of the first electronic desktop calculators in history purposely designed to be programmable. [ 6 ] [ 7 ] [ 3 ] Programma 101 was officially launched at the 1964 New York World's Fair , attracting major interest from the public and the press.

  6. Soroban - Wikipedia

    en.wikipedia.org/wiki/Soroban

    A suanpan (top) and a soroban (bottom). The two abaci seen here are of standard size and have thirteen rods each. Another variant of soroban. The soroban is composed of an odd number of columns or rods, each having beads: one separate bead having a value of five, called go-dama (五玉, ごだま, "five-bead") and four beads each having a value of one, called ichi-dama (一玉, いちだま ...

  7. Mechanical calculator - Wikipedia

    en.wikipedia.org/wiki/Mechanical_calculator

    The comptometer-type calculator was the first machine to receive an all-electronic calculator engine in 1961 (the ANITA mark VII released by Sumlock comptometer of the UK). In 1890 W. T. Odhner got the rights to manufacture his calculator back from Königsberger & C , which had held them since it was first patented in 1878, but had not really ...

  8. Stepped reckoner - Wikipedia

    en.wikipedia.org/wiki/Stepped_reckoner

    The stepped reckoner or Leibniz calculator was a mechanical calculator invented by the German mathematician Gottfried Wilhelm Leibniz (started in 1673, when he presented a wooden model to the Royal Society of London [2] and completed in 1694). [1]

  9. Slide rule - Wikipedia

    en.wikipedia.org/wiki/Slide_rule

    Others keep their old slide rules out of a sense of nostalgia, or collect them as a hobby. [ 45 ] A popular collectible model is the Keuffel & Esser Deci-Lon , a premium scientific and engineering slide rule available both in a ten-inch (25 cm) "regular" ( Deci-Lon 10 ) and a five-inch "pocket" ( Deci-Lon 5 ) variant.