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Mathematical Treasure: Roman Finger Numerals

Author(s): 
Frank J. Swetz (The Pennsylvania State University)

Aulus Persius Flaccus (known today as Persius, 34-62 CE) and Decimus Junius Juvenalis (known today as Juvenal, fl. 1st - 2nd century CE) were Roman poets and satirists. They wrote about the Roman abacus and the system of finger numerals in use at their time. Oxford scholar Barten Holyday (1593-1661) translated their writings for an English audience; his translation was published posthumously in 1673.

Title page to Decimus Junius Juvenalis and Aulus Persius Flaccus, translated by Barton Holyday, 1673

The tenth satire of Juvenal contained the line “…and now count his years on this Right hand!” In an endnote to this passage, Holyday provided the reader with a lengthy explanation of Roman finger numeral gestures, including the following chart:

Diagram of Roman finger numeral gestures from Decimus Junius Juvenalis and Aulus Persius Flaccus, translated by Barton Holyday, 1673

The images above were obtained through the courtesy of the Erwin Tomash Library on the History of Computing, Charles Babbage Institute, University of Minnesota.

Erwin Tomash (1921-2012) was a pioneering computer scientist, helping launch the U.S. computer industry from the 1940s onward. During the 1970s he became interested in the history of computer science, and founded the Charles Babbage Society, and its research arm, the Charles Babbage Institute. The Institute, an archive and research center, is housed at the University of Minnesota. Its Erwin Tomash Library on the History of Computing began with Tomash's 2009 donation to the Institute of much of his own collection of rare books from the history of mathematics and computing. (Source: Jeffrey R. Yost, Computer Industry Pioneer: Erwin Tomash (1921-2012), IEEE Annals of the History of Computing, April-June 2013, 4-7.)

Index to Mathematical Treasures

Frank J. Swetz (The Pennsylvania State University), "Mathematical Treasure: Roman Finger Numerals," Convergence (August 2018)

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