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The Ken-Add Manual Calculator from the 1950’s Was Made in Duluth and is now in the National Museum of American History


Does anyone remember this? It is the Ken-Add manual calculator or adding machine that was manufactured by the Ken-Add Machine Co. based right here in Duluth.

The company has since disappeared, but the Ken-Add calculator has a place in American history in a collection at the Smithsonian National Museum of American History, according to their website:

This four-wheeled stylus-operated adding machine has two copper-colored wheels for cents and two silver-colored wheels for dollars. There are numbers on the cover around each wheel. No complementary digits are indicated. Above the wheels are four windows that indicate the total. At the back is a plastic container for the metal stylus. Inside the lid of the case is a so-called magic slate for jotting down and erasing numbers. The adding machine, stylus, and slate fit in an aluminum case.

An account of the Ken + Add appeared in Mathematics Teacher in December 1952, where it was recommended not only as a practical adding machine but as a fascinating toy and an aid to arithmetic teaching. It was advertised in Arithmetic Teacher as late as 1956.


You can find this randomly on eBay and other collectible websites. Does anyone have any memories of either this machine or the company based here in Duluth? If you do, please share below.

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