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  2. Abacus - Wikipedia

    en.wikipedia.org/wiki/Abacus

    Each bead represents one unit (e.g. 74 can be represented by shifting all beads on 7 wires and 4 beads on the 8th wire, so numbers up to 100 may be represented). In the bead frame shown, the gap between the 5th and 6th wire, corresponding to the color change between the 5th and the 6th bead on each wire, suggests the latter use.

  3. 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 ...

  4. 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 ...

  5. 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 ...

  6. 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]

  7. 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.

  8. Prehistoric bead — nearly 13,000 years old — found in WY. It ...

    www.aol.com/prehistoric-bead-nearly-13-000...

    The bead is made of hare bone, providing experts with the first solid evidence that people in the Clovis era, a prehistoric era in North America, used bones from the rabbit cousin for personal ...

  9. 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