"The Arithma Addiator is one of the earlier calculators. Using the the pen-like brass stick that you can see clipped to its left side, the user would perform calculations by inserting the tapered end into the slots next to the numbers. The top set of numbers would be used for addition, and the bottom for subtraction, with the total displayed in the center frame. This calculator was in production in 1962, and was relatively cheap, normally costing under five dollars."
Source: System Source - Computer Museum

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