Addiator Duplex

This notched band adder is made of steel painted black, gold, and white. It has a steel stylus and a brown leather case. The front of the instrument has eight columns of numbers with a band under each column. A hook at the top of each column allows carrying and a ninth band allows carrying from the eighth column. Sums as large as nine digits are displayed in round openings above the columns. On the back are eight columns of numbers for doing subtraction. A zeroing bar extends across the bottom of the back (the top of the front).
The firm of Carl Keubler produced adders under the name "Addiator" in Berlin (later West Berlin) from 1920 until the 1980s. This is one of three versions of the Addiator in the Smithsonian collections.
Reference: Martin Reese, Historische Buerowelt, 43 (September 1995).
Currently not on view
Object Name
adder in case
date made
ca 1955
Addiator G.m.b.H.
Physical Description
steel (overall material)
leather (overall material)
overall: .5 cm x 8 cm x 12.7 cm; 3/16 in x 3 5/32 in x 5 in
place made
Deutschland: Berlin, Berlin
ID Number
accession number
catalog number
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center


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