![]() Some "old" methods to multiply or divide decimal numbers use those extra beads like the "Extra Bead technique" or "Suspended Bead technique". In fact, to represent decimal numbers and add or subtract such numbers, one strictly needs only one upper bead and four lower beads on each column. If one compares the suanpan to the soroban which is a 1:4 abacus, one might think there are two "extra" beads in each column. The suanpan is a 2:5 abacus: two heaven beads and five earth beads. The columns are much like the places in Indian numerals: one of the columns, usually the rightmost, represents the ones place to the left of it are the tens, hundreds, thousands place, and so on, and if there are any columns to the right of it, they are the tenths place, hundredths place, and so on. The ones in the upper deck are sometimes called heaven beads and carry a value of 5 in their column. The ones in the lower deck are sometimes called earth beads or water beads, and carry a value of 1 in their column. There are two types of beads on the suanpan, those in the lower deck, below the separator beam, and those in the upper deck above it. Instead of running on wires as in the Chinese and Japanese models, the beads of Roman model run in grooves, presumably more reliable since the wires could be bent.Īnother possible source of the suanpan is Chinese counting rods, which operated with a place value decimal system with empty spot as zero. Where the Roman model and Chinese model (like most modern Japanese) has 4 plus 1 bead per decimal place, the old version of the Chinese suanpan has 5 plus 2, allowing less challenging arithmetic algorithms. However, no direct connection can be demonstrated, and the similarity of the abaci could be coincidental, both ultimately arising from counting with five fingers per hand. ![]() The evident similarity of the Roman abacus to the Chinese one suggests that one must have inspired the other, as there is strong evidence of a trade relationship between the Roman Empire and China. Ī 5+1 suanpan appeared in Ming dynasty, an illustration in a 1573 book on suanpan showed a suanpan with one bead on top and five beads at the bottom. However, the identification of the object as an abacus is a matter of some debate. The long scroll Along the River During Qing Ming Festival painted by Zhang Zeduan (1085–1145) during the Song Dynasty (960-1279) might contain a suanpan beside an account book and doctor's prescriptions on the counter of an apothecary. People move the beads to do the calculation. One in the upper part represents five and each of four in the lower part represents one. As it described, the original abacus had five beads ( suan zhu) bunched by a stick in each column, separated by a transverse rod, and arrayed in a wooden rectangle box. ![]() The word "abacus" was first mentioned by Xu Yue (160–220) in his book suanshu jiyi (算数记遗), or Notes on Traditions of Arithmetic Methods, in Han Dynasty. This replaces clearing the beads by hand, or quickly rotating the suanpan around its horizontal center line to clear the beads by centrifugal force. When the clear-all button is pressed, two mechanical levers push the top row beads to the top position and the bottom row beads to the bottom position, thus clearing all numbers to zero. The modern suanpan has 4+1 beads, colored beads to indicate position and a clear-all button. Unlike the simple counting board used in elementary schools, very efficient suanpan techniques have been developed to do multiplication, division, addition, subtraction, square root and cube root operations at high speed. Suanpans can be used for functions other than counting. The suanpan can be reset to the starting position instantly by a quick jerk around the horizontal axis to spin all the beads away from the horizontal beam at the center. The beads are counted by moving them up or down towards the beam. The beads are usually rounded and made of a hardwood. There are two beads on each rod in the upper deck and five beads on each rod in the bottom deck. Usually, a suanpan is about 20 cm (8 in) tall and it comes in various widths depending on the application. However, the exact design of this suanpan is not known. ![]() The suanpan ( simplified Chinese: 算盘 traditional Chinese: 算盤 pinyin: suànpán), also spelled suan pan or souanpan ) is an abacus of Chinese origin first described in a 190 CE book of the Eastern Han Dynasty, namely Supplementary Notes on the Art of Figures written by Xu Yue. ![]()
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