Roman abacus
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The Roman hand abacus was one of the earliest known portable calculating devices, used in the Roman world. It was a base-10 form of the abacus, with movable beads held in slots rather than loose count
A reconstruction of a Roman hand abacus, made by the RGZ Museum in Mainz, 1977. The original is bronze and is held by the Bibliothèque nationale de France, in Paris. This example is missing many counter beads.
Velser's reconstruction of Roman abacus (ca. 1600)
Representable fractions of an uncia under each interpretation
Roman numerals
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Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Like many other ancient numeral syst
Roman abacus
…lineage is not documented. Its beads represented values in decimal place-value columns, allowing calculations to be carried out on the device, while Roman numerals were used mainly to record results. The device also included positions for fractional values used in Roman measures and Roman currency, especially the…
Roman numerals on stern of the ship Cutty Sark showing draught in feet. The numbers range from 13 to 22, from bottom to top.
A clock face with the Roman numerals typical for clocks, in Bad Salzdetfurth, Germany
Epitaph of centurion Marcus Caelius, showing "XIIX"
Padlock used on the north gate of the Irish town of Athlone. "1613" in the date is rendered XVIXIII, (literally "16, 13") instead of MDCXIII.