The Roman Abacus (Abacus)
The columns contain different number values. The lower four stones have the values 1 to 4 and the upper stone has the value 5.
In column I the numbers from 0 to 9 can be represented, in column X the numbers 10 to 90, in column C the numbers 100 to 900 and so on. To the right of the I column in the 8th column is the "Uncia" row, which is not in the decimal system but in the duodecimal system. Here the fraction values from 1/12 to 11/12 can be displayed. In the right, small column, the numeral signs for a semuncia (half ounce, 1/24), a quarter ounce (sicilius ( 1/48) and for the third ounce (duella, 1/36) can be found. For the half-ounce, one button was necessary, since two half-ounces make a whole uncia; the same is true for the quarter-ounce, where two then equal a half-ounce. For the one-third ounce, on the other hand, two buttons were provided.
Thus, the device has the impressive capacity to calculate up to 10,000,000, including decimal places!
A small introduction to the display and handling of an abacus can be found under
- size approx. 30x20cm
- made of beech wood
- incl. calculating stones made of glass
- fully functional
- incl. calculating stones
Forum Traiani ® registered trademark
R. Fellmann, Roman arithmetic tables made of bronze. Ancient World 14, 1, 1983, 36-40
Kretzschmar, Fritz ; Heinsius, Elli: On some representations of ancient Roman arithmetic boards. - Pp. 96-108, pl. 3-4