Ken + Add Adding Machine


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. The instrument is marked: Ken + Add MACHINES CO. DULUTH, MINN. U.S.A. PATENT APPLIED FOR.

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.


P. A. Kidwell, A. Ackerberg-Hastings, and D. L. Roberts, Tools of American Mathematics Teaching 1800-2000 , Baltimore: Johns Hopkins University Press, 2008, pp. 248-249.

Date Made: 1950s

Maker: Ken + Add Machines Co.

Location: Currently not on view

Place Made: United States: Minnesota, Duluth

Subject: Mathematics


See more items in: Medicine and Science: Mathematics, Adding Machines, Science & Mathematics


Exhibition Location:

Credit Line: Gift of Robert K. Otnes

Data Source: National Museum of American History

Id Number: 2005.0278.01Catalog Number: 2005.0278.01Accession Number: 2005.0278

Object Name: adding machine

Physical Description: metal (overall material)plastic (overall material)paper (overall material)Measurements: overall: 1 cm x 13.2 cm x 6.6 cm; 13/32 in x 5 3/16 in x 2 19/32 in


Record Id: nmah_1299607

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