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© 2000-2014   Gérard P. Michon, Ph.D.

Roman Numerals


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Related Links (Outside this Site)

Roman Numerals and Dates by Paul Lewis ("Deadline").
Roman Numeral and Date Conversion by Steven Gibbs.
Date converter, Latin expressions and dictionary from 24 Hour Translations.
Self-referential sentences using Roman numerals.
How did the Romans express fractions?  Answer by Jim Calvert, Exeter Devon.

Trivia :   In 2006, a reporter contacted me to confirm that it wasn't proper to advertise the 2006 Super Bowl as "XXXX".  The correct Roman numerals (XL)  were used for the rest of the advertising campaign.  Starting with Super Ball XLI, on February 4, 2007,  Numericana.com  has received an abnormal number of visits from football fans who take a sudden interest in Roman numerals during Super-Bowl Sunday.  On a regular Sunday back then, we'd have been expecting about 1600 visits.  During Super-Bowl XLI, we had 4014...  The same phenomenon happens every year:  On the day of  Super-Bowl XLII  (February 3, 2008)  Numericana had 4824 visits.  For Superbowl XLIII (February 1, 2009)  3447 visits were logged.  On Super Bowl XLIV  (February 7, 2010)  4803 hits were recorded.  On Feruary 6, 2011  (Super Bowl XLV)  all records were shattered,  in part because so many people were wondering why VL isn't a correct replacement for XLV...  Around kickoff time, our little server buckled under a peak load of one hit per second.  By the end of the day, we had logged 15278 queries  (more than 90% of those about XLV).  That was more than three times the previous one-day record at Numericana...
 
This yearly frenzy caught the attention of  Leanne Italie  (Associated Press)  who interviewed me a week before Super Bowl XLVI.  Her story was picked up all over the place and inspired other articles, included translations in French and Chinese.
 
Super Bowl XLVI took place on February 5, 2012 at  Lucas Oil Stadium  in Indianapolis.  When the dust settled, after the victory of the New-York Giants, all traffic records had been shattered again at Numericana:  21399 hits in a single day  (midnight to midnight).
 
For  Super Bowl XLVII  (47)  the traffic more than doubled again:  47237 visits in  one  day  (February 3, 2013).  The stressed server worked flawlessly, so did the counter.
 
On Sunday Feb. 2, 2014  (Superbowl XLVIII = 48)  we "only" had 7157 hits  (just 15% of the all-time record from the previous year)...  Yet, it was our 4th busiest day in 14 years!
 
Looking forward to Superbowl XLIX in 2015 and...  L  (in February 2016).
Yes Virginia,  XLIX  (Super Bowl 2015)  means 49  (L  is 50, but  IL  is incorrect).   ;-)

 
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Roman Numerals

I=1, V=5, X=10, L=50, C=100, D=500, M=1000,
archaic: 5000=5000, 10000=10000, 50000=50000, 100000=100000.
1Ii
2IIii
3IIIiii
4IViv
5Vv
6VIvi
7VIIvii
8VIIIviii
9IXix
10Xx
11XIxi
12XIIxii
13XIIIxiii
14XIVxiv
15XVxv
16XVIxvi
17XVIIxvii
18XVIIIxviii
19XIXxix
20XXxx
21XXIxxi
22XXIIxxii
23XXIIIxxiii
24XXIVxxiv
25XXVxxv
26XXVIxxvi
27XXVIIxxvii
28XXVIIIxxviii
29XXIXxxix
30XXXxxx
31XXXIxxxi
32XXXIIxxxii
33XXXIIIxxxiii
34XXXIVxxxiv
35XXXVxxxv
36XXXVIxxxvi
37XXXVIIxxxvii
38XXXVIIIxxxviii
39XXXIXxxxix
40XLxl
41XLIxli
42XLIIxlii
43XLIIIxliii
44XLIVxliv
45XLVxlv
46XLVIxlvi
47XLVIIxlvii
48XLVIIIxlviii
49XLIXxlix
50Ll

2011 = MMXI,  2012 = MMXII,  2013 = MMXIII,  2014 = MMXIV,  etc.
Superbowl numbers:  XLVII = 47 (Feb. 2013),  XLVIII = 48 (Feb. 2014),  etc.

Subtractive Principle:

Any numeral is counted positively unless there's a larger numeral anywhere to its right, in which case it is counted negatively.  However, proper Roman numbers are subject to the following restrictions about the applicability of the subtractive principle.

The use of the subtractive principle has always been optional. Its systematic use is fairly modern.  For example, it's acceptable to use IIII instead of IV, as is usually done on clockfaces (to "balance" their left and right halves, so we're told).

The subtractive principle (a subtrahend preceding a minuend) may apply:

  • Only to a numeral (the subtrahend) that is a power of ten (I, X or C).
    For example, "VL" is not a valid representation of 45 (XLV is correct).
  • Only when the subtrahend precedes a minuend no more than ten times larger.
    For example, "IL" is not a valid representation of 49 (XLIX is correct).
  • Only if any numeral preceding the subtrahend is at least ten times larger.
    For example, "VIX" is not a valid representation of 14 (XIV is correct), and "IIX" is not correct for 8 (VIII is correct).
  • Only if any numeral following the minuend is smaller than the subtrahend.
    For example, "XCL" is not a valid representation of 140 (CXL is correct).

Multiplicative Principle (medieval numeration only):

When the second of the above conditions was not met in front of an M (or C) numeral, a medieval convention was that the number to the left of M (or C) was the number of thousands (or hundreds) which was to be added to the number located to the right of M (or C).  When this convention is intended, it's best to write M (or C) as a superscript (as explained below).

For example, CM means 900, but LLM could only translate into 100000.  (This is a rather dubious example which is  not  based on an historical instance.)

Do not assume that everyone is an expert at medieval numeration...  It's more likely that someone writing  MXMI  intends  1991,  rather than  1010001 = MXMI.

A medieval writer would definitely have hesitated to use this multiplicative convention beyond  XCIXM (99000)  or  XCIXMCMXCIX (99999).  Something like  MIMIMI (1001001001)  would have sickened most medieval minds!


(2013-04-15)   Converting from decimal numbers to Roman numerals.
Here's a simple foolproof way:

All of the above rules for standard Roman numeration can be  precisely  summarized by the following conversion table  (for numbers up to 9999).

Matching multi-digit decimal numbers
with their Roman counterparts
:
  Digit  Thousands  Hundreds  Tens  Units  
0     
1 MCXI
2 MMCCXXII
3 MMMCCCXXXIII
4 MMMMCDXLIV
5 MMMMMDLV
6 MMMMMMDCLXVI
7 MMMMMMMDCCLXXVII
8 MMMMMMMMDCCC  LXXX  VIII
9  MMMMMMMMM CMXCIX

For example, the Roman representation of  4096  is the juxtaposition of the "4" entry from the "thousands" column  (MMMM)  the "9" entry from the "tens"  (XC)  and the "6" entry from the "units" column  (VI) :

4096   =   MMMMXCVI

Likewise,  you convert  2013  by concatenating  MM,  X and  III :

2013   =   MMXIII

One last example:   1956   =   M + CM + L + VI   =   MCMLVI.

For (much) larger numbers, read on...


kdomenick (2001-04-02)   What are the Roman numerals for 18 034?

There are several correct answers for 18034, including the awkward:

MMMMMMMMMMMMMMMMMMXXXIV

The Roman system of numeration is based on an earlier Etruscan system which was sometimes also used by the ancient Romans for slightly larger numbers.  The archaic symbol 10000 used for 10000 was a large "m" with 5 legs instead of 3, and it may be typed as "((I))".  The symbol 100000 for the number 100000 had 7 legs and may be typed as "(((I)))".  The obvious extension to 9 legs or more was apparently not used, so the Roman representation of a million would consist of 10 times a 7-legged "m":

100000 100000 100000 100000 100000 100000 100000 100000 100000 100000

Incidentally, the right half of such symbols was used to represent half the corresponding number. For example, the numeral for 5000 was 5000, which may be typed as "I))".  The numeral for 500 was 500, it could be typed as "I)", but it got transliterated into "D", the same way 1000 became "M" to represent 1000 (a mnemotechnical bonus was that M is the initial of "mille", the Latin word for 1000).  In print or engravings, such archaic numbers often appear with a regular "C" instead of our "(" and an upside-down "C" instead of our ")" (which is called an apostrophus in this context), so that you will find 1000 instead of "M" or "1000" in the publication dates of some early books.  There are about a dozen (!) similar graphical variations on this archaic theme...

The basic rules of Roman numeration apply to such symbols: Any numeral is counted positively unless there's a larger numeral anywhere to its right, in which case it is counted negatively.  (As explained above, proper Roman numbers are subject to precise restrictions when the numerals do not appear in decreasing order.) Using the above Roman/Etruscan numerals for 10000 and 5000, the number  18034  translates into:

10000 5000 MMMXXXIV    which could be typed    ((I)) I)) MMMXXXIV

This archaic system was replaced by one which uses only 7 basic symbols (I=1, V=5, X=10, L=50, C=100, D=500, M=1000), with the convention that putting an overbar  (a vinculum)  over a basic number would denote a value 1000 times as large.  It became customary to add little downward-pointing corner marks to such a multiplying vinculum because the straight vinculum was also used (following the Greek custom) simply to distinguish numerals from regular letters, within ordinary text.  Skipping that optional flourish, any Roman accountant would simply have expressed 18034 as:

vinculum
XVIII  XXXIV

The convention about corner marks on the vinculum caused another problem: If those marks were too large, the whole thing could be misread as an upper half-frame, which indicated multiplication by 100000 instead!  This ambiguity is the source of a famous dispute about the testament of the widow of Emperor Octavian (Livia Drusilla, 58 BC-AD 29) who willed either 500 000 or 50 000 000 sesterces (most probably the latter) to the futur Emperor Galba, whereas her son, the reigning Emperor Tiberius, was the residual heir.  The historian Suetonius reports that quia notata non praescripta erat summa (because the intended sum had not been written out in words), Tiberius could rule that only the lesser amount was owed.  Suetonius adds that Galba did not even receive that!  The inscription in Livia's testament resembled the middle one below (she did use "CCCCC" instead of the more compact "D" numeral):

    vinculum           vinculum vinculum vinculum           vinculum vinculum vinculum
CCCCC CCCCC CCCCC
500
or
500 000
500 000
or
50 000 000
50 000 000

Apparently, the historical record does not show any instances of multiple overstrikes to indicate successive multiplications by 1000 and/or 100 000 (stay away from this dubious extension of the system).  When dealing with the very large amounts involved in public affairs, the Romans understood that the "basic" unit was centena milia (100 000, one hundred thousand [sesterces]).  As Emperor Vespasian took office in AD 69, the amount of money in the state treasury was reported to him as quadringenties milies (400 times 1000 times) namely: 40 000 000 000 sesterces.

Finally, as noted above, it's worth mentioning that the familiar subtractive principle (according to which a numeral appearing before a higher one is to be counted negatively) was not always strictly respected in medieval or ancient times.  Instead, smaller numerals appearing before M or C may have meant multiplication (by 1000 or 100) instead, so that VIIC would mean 700 and VIM would mean 6000 (this is especially true in the context of Common Era dates; CE = Common Era = Christian Era = AD = Anno Domini). The unambiguous typography for this multiplicative convention is to put C or M as superscripts (VIIC or VI), which is consistent with ancient usage.  The use of a dot has also been advocated (VII.C or VI.M), but it is less than satisfying. This gives yet another way to represent 18034, namely:

XVIIIMXXXIV

The  (recommended)  superscripting is not strictly necessary because the unsuperscripted  XVIIIMXXXIV  wouldn't otherwise be a valid number...


psudo (2002-03-01; e-mail)
Your discussion of roman numerals left me wondering if combinations of superscripting and overstriking, say, would be an acceptable stretch of the Roman system to represent larger numbers...

Extensions of Roman numeration have been toyed with, but the historical record doesn't reveal any  actual  usage of an extended system.

Multiple overstriking, or combinations of overstriking and superscripting, are nowhere to be found, neither are multiple-legged symbols beyond 100000, or equivalent parentheses combinations beyond (((I))).  I am not even sure whether overstriking was ever used with larger symbols like 100000 (tell me).

Such extensions would be unambiguous enough to be interpreted correctly, but they are just not a proper part of the system.

This used to be a genuine problem when Roman numeration was dominant in the Western World.  That's no longer the case, though, and there would be little point in devising a new extension to this antiquated system, now best reserved to the mundane numbering of...

  • Bearers of the same name.  (Popes, kings, family members, etc.)
  • Preface pages.
  • Book chapters.
  • Copyright years.
  • Superbowl events.

Nothing beyond  MMMCMXCIX  (3999)  is needed anytime soon.


(2013-04-15)   Trivia Question
What year has required the longest string of Roman numerals, so far?

Answer:  MDCCCLXXXVIII  (1888).  The record will be broken in  2888.


Nicholas Stevenson (2002-10-07; e-mail)
I am currently translating the Chronographus Anni CCCLIIII.  It has a few strange numbers like CCCLXIIS and LXXXVIIS dealing with money and measurement.  I am not sure what the S represents [...]

"S" probably stands for "semis" (one half), however...

In both of your examples, we could also be dealing with the abbreviation for sesterce "IIS" (this later became "HS", which is better and less ambiguous).  This symbol comes from the fact that a sesterce was originally two and a half asses  (when the as was still the primary Roman monetary unit).  If that's the case, CCCLXIIS (or LXXXVIIS) would be 360 (or 85) sesterces.

I think the abbreviation "IIS" was still used when the "Chronography of 354" was written.  (Please tell me whatever you may know.)

On 2002-10-07, Nicholas Stevenson wrote:
I thought about the money aspect of the symbol S, but it doesn't explain what it means in terms of measurement.  I dont think that it is a symbol for money, but perhaps it does mean half a denarius, or half a foot.  I'll give you both examples in full:
  • Congiarium dedit d LXXIIS.
    [Where "d" replaces the original symbol for denarii.] 
  • ... et oboliscum cum sua sibi base, qui est in circo maximo, altum edes LXXXVIIS.
I just found something that probably explains it in one of my grammar books:  "As an abbreviation, S denotes sacrum, semis, sibi suis, etc."  I think S must [simply] mean a half.
Nick Stevenson


(2014-03-11)   Duodecimal Roman fractions are all but forgotten.
The rudimentary Roman representation of numbers less than unity.

One twelfth of a unit was an  uncia ;  one sixth of that was a  sextula.

The names of most other Roman fractions are given in the first column of the following table,  which appears on page 283 of  Mathématiques et mathématiciens  (Editions Magnard, 1959)  by  Pierre Dedron (1887-1970)  and  Jean Itard (1902-1979).

The second column gives the glyphs found in the works of  Victorius of Aquitaine  (fifth century AD).  The third column corresponds to the Basel edition  (1558)  of the Latin translation of Euclid's  Elements  by  Johannes Campanus of Novara  (1220-1296).  The last two columns provide the ratio of the quantity to one whole unit and to  one ounce  (1/12)  respectively.

Libra         Uncia      
 Roman fractions

The smallest quantity expressible with the above Roman fractions is the difference between a  siliqua  and a  chalcus, which amounts to  1/576  of an ounce  (or  1/6912 of a whole).  The  cerates, siliqua and chalcus are respectively equal to 6, 4 and 3 of those untabulated units.  That elementary unit was apparently known as  lentes  (symbol unknown)  and it was to a whole  (namely, to an as or to a libra)  nearly what a grain is to a modern pound  (1 lb is 7000 grains).  The Romans didn't consider anything smaller.

The latest names of small Latin fractions are loosely inspired by Greek coins or weights:  In ancient Athens, the equivalences were 6 obols to the drachma, 8 chalkoi to the obol and 7 lepta (or mites) to the chalcos.

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