This full-keyboard direct multiplication non-printing electric calculating machine has an iron and steel case painted black, The nine columns of plastic black and white keys are colored according to ...

Invented by Leonardo Torres in 1920, the Torres calculating machine is a machine that solves essential addition, subtraction, multiplication, and division problems using a simple manner. It was a ...

This compact cylindrical handheld calculating machine has black metal sides and a plastic top and operating handle. Eight slots along the side of the cylinder hold levers that are pulled down to set ...

It’s no bigger than a drinking glass, and it fits easily in the palm of the hand. It resembles a pepper grinder—or perhaps a hand grenade. The diminutive “Curta” is a striking machine, a mechanical ...

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