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Ellis Adding Typewriter, 1910 onwards...
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"The Millionaire" Calculating Machine, 1912...
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3 American Adding Machines...
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Edwin Thacher's Cylindrical Slide Rule Calcul...
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4 Electric Calculating Machines...
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6 Toothed Wheel Adders...
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Chinese Circular Abacus "Suan Pan", c. 1936...
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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...
