Exactus Mini-Add

This black and silver-colored metal instrument is a notched band adder with nine bands, eight columns, and a nine-digit display. Its bracket-shaped columns are color-coded for dollars and cents. A plate attached to the top which covers the lower part, for use in addition, or pivots and covers the upper part, for use in subtraction. Across the top is a zeroing bar. The device includes a metal stylus and fits in a black plastic case which also holds several yellowing sheets of paper. Instructions are stored with the object.
This British adder was received at the Smithsonian in about 1970. It seems likely that it was made in the mid-20th century.
Currently not on view
Object Name
date made
ca 1950
Physical Description
metal (overall material)
plastic (overall material)
overall: 1 cm x 7.9 cm x 11.5 cm; 13/32 in x 3 1/8 in x 4 17/32 in
place made
United Kingdom: Great Britain
United Kingdom
ID Number
accession number
catalog number
Science & Mathematics
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Howard Chapelle
Additional Media

Visitor Comments

6/17/2014 7:25:51 AM
The UK version had a different flap and perforations to allow for adding and subtracting in sterling £.s.d. (12d = 1s, 20s = 1£)
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