The term seems to derive from the abacus ABQ Semitic word meaning "dust": This fact leads us to think that in other regions other than China that instrument is born of a basin containing dust or sand used as a "tablet for the calculation." However we do not have specific dates in order to identify where and how the abacus is born. We can only say that the Arabs had ten abacus beads strung on each wire and no center pole, while the Chinese abacus was strung on each wire five balls separated by two upper and lower rod. Each of the balls on a wire above the abacus in China is equivalent to five balls on the lower edge. To find a number you slide balls placing them all'asticciola appropriate separation.
In Japanese elementary schools soroban is called and is still used today. E 'consisting of 25 vertical rows of five balls divided into four, plus one from a horizontal pole. Each ball under the bar corresponds to a unit, and each ball on a pole to a quintet. By moving the balls with carry-type semidecimale you can perform all arithmetic operations, calculating up to several millions, but also many operations of algebra, with speeds as fast as permitted by the pocket calculator, so that is used by many retailers, postal employees and banks (especially the change of currency).
calculations with the abacus
To see how they could be carried out calculations using the abacus, I tried to perform the four arithmetic operations with the process learned in school, but using the abacus instead of a pen and paper: the attempt is successful, although it requires a some skill in mental arithmetic, and this leads me to believe that the procedures used were not very different from ours.
L 'addition, of course, no problem: when the chips in a box, the value reached 10, simply replace them with a coin in the box Vivina left, and continue. For subtraction we follow a reverse procedure, taking a chip from the box to the left when the figure of the coin box sottraendoun left when the figure is higher than that of subtracting the minuend. The proliferation is already more complicated if the multiplier has more digits, you should do on the box of the relevant power of 10, like we do when we move one place to the left of each successive partial product. The operation
more complex the division, can not be put "in the column" intermediate results, but in this case was applicable to our calculation procedure, first testing a quotient with the first digit of the divisor, seeing if the next digit of the divisor "is" the next dividend, and so on, until the rest.
"The abacus proxy multi-sensory experience, in fact, the abaca balls move sees, hears the tinkle when bumping against each other, and perceive them as a whole. Surely there is another digital computer that has un'attendibilità so high in proportion to the low cost of purchase and maintenance. " Martin Gardner
NB The image you see above is the Soroban I along with my fellow group of mathematics, "TEAM ALONSO" , we have built to the point T07 examination.
(On this point I decided to add on my blog, as well as the image, some curiosity about this tool in Japan.)
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