Magic-Brain Calculator

From at least the 19th century, people have been intrigued by the ability of computing devices to assist in mental processes. The name of the “Magic-Brain Calculator” suggests this enthusiasm, although the capabilities of the instrument were quite modest.
The Japanese-made notched band adder has a red plastic back, a silver-colored metal cover plate, and six fasteners around the edges that hold it together. Six bracket-shaped columns allow for borrowing and carrying. A row of seven holes above the columns shows the result. The bands fit rather loosely in the channels of the plastic back. A zeroing bar runs across the top and a stylus attahes to the side. The object is marked: MAGIC-BRAIN CALCULATOR. On the back It is marked: MADE IN JAPAN. For instructions, see 1987.0375.02.
References: Popular Science, February, 1962, vol. 180, p. 20. This ad indicates that at that time the Magic-Brain Calculator cost $.98 and was distributed from the Sunset Building, Beverly Hills, California.
P. Kidwell, “Adders Made and Used in the United States,” Rittenhouse, 8, (1994): pp. 78-96.
Currently not on view
date made
date distributed
Sunset House
place made
place distributed
United States: California, Beverly Hills
Physical Description
plastic (overall material)
metal (overall material)
overall: 1 cm x 7 cm x 14 cm; 13/32 in x 2 3/4 in x 5 1/2 in
ID Number
catalog number
accession number
Credit Line
Gift of William S. Snyder
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center


Interestingly the way you multiply is by adding the number multiple times. ex. 7X3 would be 7+7+7= 21. You also "divide" by subtracting the (the 'divided by' number) multiples of time, as you make sure to keep a tally of the number of times that number is subtracted from the larger number. At some point you'll have the reminder and the tally on a piece of paper. Also of note, it is easy to get the black columns of numbers on the device mixed up with the "white" column. With enough practice you can get it down pretty good. A good way to practice is to have a regular calculator to check your work.
Bought mine @ Ben Franklins in 1973. Still got it.

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