<P> The number zero does not have its own Roman numeral, but the word nulla (the Latin word meaning "none") was used by medieval scholars in lieu of 0 . Dionysius Exiguus was known to use nulla alongside Roman numerals in 525 . About 725, Bede or one of his colleagues used the letter N, the initial of nulla or of nihil (the Latin word for "nothing"), in a table of epacts, all written in Roman numerals . </P> <P> Though the Romans used a decimal system for whole numbers, reflecting how they counted in Latin, they used a duodecimal system for fractions, because the divisibility of twelve (12 = 2 × 3) makes it easier to handle the common fractions of 1 / 3 and 1 / 4 than does a system based on ten (10 = 2 × 5). On coins, many of which had values that were duodecimal fractions of the unit as, they used a tally - like notational system based on twelfths and halves . A dot () indicated an uncia "twelfth", the source of the English words inch and ounce; dots were repeated for fractions up to five twelfths . Six twelfths (one half) was abbreviated as the letter S for semis "half". Uncia dots were added to S for fractions from seven to eleven twelfths, just as tallies were added to V for whole numbers from six to nine . </P> <P> Each fraction from 1 / 12 to 12 / 12 had a name in Roman times; these corresponded to the names of the related coins: </P> <Table> <Tr> <Th> Fraction </Th> <Th> Roman numeral </Th> <Th> Name (nominative and genitive) </Th> <Th> Meaning </Th> </Tr> <Tr> <Td> 1 / 12 </Td> <Td> </Td> <Td> Uncia, unciae </Td> <Td> "Ounce" </Td> </Tr> <Tr> <Td> 2 / 12 = 1 / 6 </Td> <Td> or: </Td> <Td> Sextans, sextantis </Td> <Td> "Sixth" </Td> </Tr> <Tr> <Td> 3 / 12 = 1 / 4 </Td> <Td> or ∴ </Td> <Td> Quadrans, quadrantis </Td> <Td> "Quarter" </Td> </Tr> <Tr> <Td> 4 / 12 = 1 / 3 </Td> <Td> or:: </Td> <Td> Triens, trientis </Td> <Td> "Third" </Td> </Tr> <Tr> <Td> 5 / 12 </Td> <Td> or:: </Td> <Td> Quincunx, quincuncis </Td> <Td> "Five - ounce" (quinque unciae → quincunx) </Td> </Tr> <Tr> <Td> 6 / 12 = 1 / 2 </Td> <Td> </Td> <Td> Semis, semissis </Td> <Td> "Half" </Td> </Tr> <Tr> <Td> 7 / 12 </Td> <Td> S </Td> <Td> Septunx, septuncis </Td> <Td> "Seven - ounce" (septem unciae → septunx) </Td> </Tr> <Tr> <Td> 8 / 12 = 2 / 3 </Td> <Td> S or S: </Td> <Td> Bes, bessis </Td> <Td> "Twice" (as in "twice a third") </Td> </Tr> <Tr> <Td> 9 / 12 = 3 / 4 </Td> <Td> S or S: </Td> <Td> Dodrans, dodrantis or nonuncium, nonuncii </Td> <Td> "Less a quarter" (de-quadrans → dodrans) or "ninth ounce" (nona uncia → nonuncium) </Td> </Tr> <Tr> <Td> 10 / 12 = 5 / 6 </Td> <Td> S or S:: </Td> <Td> Dextans, dextantis or decunx, decuncis </Td> <Td> "Less a sixth" (de-sextans → dextans) or "ten ounces" (decem unciae → decunx) </Td> </Tr> <Tr> <Td> 11 / 12 </Td> <Td> S or S:: </Td> <Td> Deunx, deuncis </Td> <Td> "Less an ounce" (de-uncia → deunx) </Td> </Tr> <Tr> <Td> 12 / 12 = 1 </Td> <Td> </Td> <Td> As, assis </Td> <Td> "Unit" </Td> </Tr> </Table>

Where did the roman numeral v come from