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Early Combination of Abacus and Chalk Board, ...
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Abacus for Teaching Purposes, c. 1900...
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Russian Stchoty Abacus, c. 1900...
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Chinese Suan Pan Duplex Abacus, c. 1940...
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Chinese Semi-Circular Abacus, c. 1936...
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Thomas de Colmar Adding Machine, 1849...
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Burkhardt Arithmometer Model H, c. 1909...
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"Curta Type II" (Grey), 1948...
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6 Calculating Machines...
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8 Mechanical Dial Adding Machines...
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The Summator Large Disc Adder, 1855...
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2 Calculating Machines, c. 1920...
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6 Spoked-Wheel Calculating Machines...
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Loga Calculating Drum, c. 1930...
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6 Spoked-Wheel Calculating Machines...
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Brass Stepped-Drum Calculating Machine Bunzel...
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Pocket Adder by Le Paute, Paris 19th Century...
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6 Calculating Machines...
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XxX ('X multiplied by X') Keyboard Calculatin...
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Prototype Laughlin Automatic Adding Machine, ...
