El Ábaco:
Los dispositivos para ayudarnos a contar y calcular aparecieron a medida que se desarrollaban los sistemas numéricos en distintas partes del mundo. Alrededor del año 3,000 a.c., mercaderes y traficantes en el Medio Oriente y a lo largo de la ruta de tráfico del mediterráneo comenzaron a utilizar el ábaco, este simple marco de madera con bolas ensartadas por alambres es aun hoy utilizado en muchas partes del mundo para realizar cálculos contables y comerciales.
Abacus and Soroban 
abacus (transparent background)
soroban transparent background)
lee abacus (transparent background)
attempts at making abacus and soroban icons (they don’t really work when they are tiny)
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single rods for soroban instruction page (transparent background)
13 reel soroban for abacus instruction page (transparent background)
15 reel soroban for abacus instruction page (transparent background)
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soroban gif animation (white background)
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Dilson Abacus: This is the abacus that accompanies the Jesse Dilson book. It measures 5.5 inches by 3.5 inches, has 9 columns and is made of a soft wood (possibly white pine) and finished with a glossy transparent laquer. The workmanship is fairly good considering the cost and volume. |
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Lee Abacus:This is the Lee Kai-chen abacus, it measures 13 inches wide and 8 inches high. The design consists of 2 abaci stacked one on top of the other. The top abacus is a 1/4 abacus with 18 columns having small pale green beads on the left half (9 columns) and white beads on the right half (9 columns). The bottom abacus is a 2/5 abacus with 13 columns having larger black beads. Note that the top frame is slightly warped and that the abacus is standing vertically– not a natural position for use (it just photographs better this way). |
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Lee Abacus, Detail 1: This is the top-left corner of the Lee abacus. |
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Lee Abacus, Detail 2: This is the bottom-left corner of the Lee abacus. Note the corner joint is a simple 45° with a metal re-inforcement nailed to the outside. The decimal place «roller» mounted on the outside of the frame is better visible from this angle. |
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Tomoe Soroban: The abacus is wrapped in a heavy plastic bag and comes in a box. It has 23 rows; being a Japanese soroban, it is a 1/4 abacus (a single bead in the upper deck and four in the lower deck). It is about 14 inches long and about 2 inches high. This abacus was a gift from the Tomoe Soroban Company. |
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Tomoe Soroban Detail: A close-up view of the Tomoe soroban. Every sixth column is marked with a white dot on both the upper and lower frame members. A black dot appears every third column on the beam (the horizontal piece that separates the upper and lower decks). |
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Three Abaci: Compare the relative sizes of the Dilson abacus, left, the Tomoe soroban, right-foreground, and the Lee abacus, background. |
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