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  2. Abacus - Wikipedia

    en.wikipedia.org/wiki/Abacus

    An abacus (pl.: abaci or abacuses), also called a counting frame, is a hand-operated calculating tool which was used from ancient times in the ancient Near East, Europe, China, and Russia, until the adoption of the Hindu–Arabic numeral system. [1] An abacus consists of a two-dimensional array of slidable beads (or similar objects). In their ...

  3. Chisanbop - Wikipedia

    en.wikipedia.org/wiki/Chisanbop

    The Chisanbop system. When a finger is touching the table, it contributes its corresponding number to a total. Chisanbop or chisenbop (from Korean chi (ji) finger + sanpŏp (sanbeop) calculation [1] 지산법/指算法), sometimes called Fingermath, [2] is a finger counting method used to perform basic mathematical operations.

  4. 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 ...

  5. Bi-quinary coded decimal - Wikipedia

    en.wikipedia.org/wiki/Bi-quinary_coded_decimal

    Japanese abacus. The right side represents 1,234,567,890 in bi-quinary: each column is one digit, with the lower beads representing "ones" and the upper beads "fives". Bi-quinary coded decimal is a numeral encoding scheme used in many abacuses and in some early computers, notably the Colossus. [2]

  6. Mental abacus - Wikipedia

    en.wikipedia.org/wiki/Mental_abacus

    Calculations can be made at great speed in this way. For example, in the Flash Anzan event at the All Japan Soroban Championship, champion Takeo Sasano was able to add fifteen three-digit numbers in just 1.7 seconds. [2] This system is being propagated in China, [3] Singapore, South Korea, Thailand, Malaysia, and Japan. Mental calculation is ...

  7. Trachtenberg system - Wikipedia

    en.wikipedia.org/wiki/Trachtenberg_system

    5 + half of 7 (3) + 5 (since the starting digit 5 is odd) + 1 (carried) = 14. Write 4, carry the 1. ... Almost all proficient abacus users are adept at doing ...

  8. Suanpan - Wikipedia

    en.wikipedia.org/wiki/Suanpan

    This 4+1 abacus works as a bi-quinary based number system (the 5+2 abacus is similar but not identical to bi-quinary) in which carries and shifting are similar to the decimal number system. Since each rod represents a digit in a decimal number, the computation capacity of the suanpan is only limited by the number of rods on the suanpan.

  9. Kaktovik numerals - Wikipedia

    en.wikipedia.org/wiki/Kaktovik_numerals

    30,561 10 3,G81 20 ÷ ÷ ÷ 61 10 31 20 = = = 501 10 151 20 30,561 10 ÷ 61 10 = 501 10 3,G81 20 ÷ 31 20 = 151 20 ÷ = (black) The divisor goes into the first two digits of the dividend one time, for a one in the quotient. (red) fits into the next two digits once (if rotated), so the next digit in the quotient is a rotated one (that is, a five). (blue) The last two digits are matched once for ...