Roman dates (years)
This article is about how the Romans counted their years, and how this system has been adopted in modern times. For an account of how the Romans calculated the days of the year, see Roman calendar (months).
From Julius Caesar's introduction of the Julian calendar in 46 BCE, the Romans used a solar calendar largely similar to our own, although it was refined in 1582 by Pope Gregory XIII to account better for leap years. This was known as the Gregorian calendar. Classical Romans identified each year by the names of the consuls who held office, as in consule Crasso 'Crassus being consul' or 'in the consulship of Crassus'. It is widely taught that they used the year (753 BCE) in which they believed the city of Rome to have been founded as a starting point; but this appears not to have been commonly used, perhaps because they realized that the date was not necessarily historically accurate. When they did, the years were numbered annō urbis conditae 'in the year of the foundation of the city [of Rome]' (or in some cases ab urbe conditā 'from the foundation of the city'), abbreviated in both cases as a.u.c.
- You may also want to see Christian calendar.
The Roman system of writing numbers is still in use in English, although it is very unfitted for mathematical purposes. For a handy table of the first twenty numbers, see numerals (Roman).
One use of this antiquated system of numbers is in writing year dates, in copyright notices and in monuments, gravestones and the like. This article hopes to show readers how the system works, so that they can work out any year for themselves..
First, there is no character for 'zero' - 0. The numbers are 'encoded as' or 'represented by' letters of the alphabet. If there is no number (or if the number is 'zero'), there is no letter.
Second, the Romans counted in units of 5 and 10. Between these numbers and their multiples, they use a system of addition and subtraction.
Each letter represents a different unit. I stands for 'one' or 1, in the usual 'Arabic' system of numerals. (Notice the difference between the 'Roman' upper case letter I and the 'Arabic' numeral 1.) 2 and 3 are represented by the same number - in the appropriate quantities. 'Two' (2) is II. 'Three' (3) is III. So far, so logical - and so easy.
The next letter to be used is V. This, which is supposed by some to represent a human hand with its fingers splayed out, stands for 'five' (5). 'Four' (4) is one less than V, so it is represented by I before the V - IV. 'Six' (6) on the other hand is one more than V, so is written with an I after the V. Similarly, 'seven' (7) is VII (5 + 2) and 'eight' (8) is VIII (5 + 3).
The number 'ten' (10) is represented by X (which can be seen as two Vs, one inverted under the other). Following the same principles, whereby a smaller number before a higher value is to be subtracted, and a smaller number after a higher value is to be added, IX is nine' (9 = 10 - 1), and 'eleven', 'twelve' and 'thirteen' are XI (10 + 1), XII (10 + 2) and XIII (10 + 3) respectively.
We continue the same system of addition and subtraction around multiples of 5. XV is 15; XIV 14, XVI 16 (10 + 5 + 1), XVII and XVIII should be clear by now.
The next step is 'twenty', XX, and its derivatives, XIX (19) and XXI for 21. The rest of the twenties are XXII, XXIII, XXIV, XXV, XXVI, XXVII, XXVIII and XXIX. The 'thirties' are the same - XXX to XXXVIII (38).
Now we introduce a new letter. L means 'fifty' (50). 40 is XL, and 39 is IXL (50 - 11, or 40 - 1). 'Sixty', 'seventy' and 'eighty' are LX, LXX and LXXX. The numbers between follow the same pattern of I, V and X as before, from XLI (41) to LXXXVIII (88). After 88, we start to subtract from 100, or C in Roman numbers. XC is 90.
500 is D, and 1,000 is M. So you may see a book dated as M DCC XCVI (if you are reading Literature or History). Now you will instantly realise that this copy was published in 1796; and that BBC television's repeated programmes dated MM were made in 2000, those saying MMI were first shown in 2001.
See also dates.