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.
Currently not on view
Object Name
adding machine
date made
Ken + Add Machines Co.
Physical Description
metal (overall material)
plastic (overall material)
paper (overall material)
overall: 1 cm x 13.2 cm x 6.6 cm; 13/32 in x 5 3/16 in x 2 19/32 in
place made
United States: Minnesota, Duluth
ID Number
catalog number
accession number
Science & Mathematics
Adding Machines
See more items in
Medicine and Science: Mathematics
Adding Machines
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Robert K. Otnes
Additional Media

Visitor Comments

3/27/2013 11:51:32 AM
I had a question about a similar piece that I have. It's almost exactly the same as this one, but it says St. Paul, Minn, USA on it instead of Duluth. Also, the lid is black metal and the base is a gold metal. I just wanted to know if anyone has seen something similar.
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