The Roll Family Windmill

Roman Numerals
A Refresher Course
Roman numerals helped kill the Roman Empire
Now they're killing us

Genealogists encounter Roman numerals in dates and in pagination. This review will cover only Roman numerals less than MMM (3,000.)

MDCCCLXXXVI

What does it mean?

There are seven letters used in modern Roman numerals
for numbers less than 3,000

I	means	1
V	means	5
X	means	10
L	means	50
C	means	100
D	means	500
M	means	1000

Sometimes lower case letters are used for pagination: i, v, x, l, c, d, and m.

The Subtraction Rule
If you use the charts below, you will not have to remember the rule

There is only one rule to remember, and that is that identical letters are only repeated three times in succession. To avoid four identical letters in succession, subtraction is used. The rule for subtraction is that if a letter is preceeded by a letter with a lesser value, the first is subtracted from the second.

IV means 5-1=4
IX means 10-1=9
XL means 50-10=40
XC means 100-10=90
CD means 500-100=400
CM means 1000-100=900

For example, to translate the Roman numeral XXXIII, find it on the chart (green). The translation is the sum of Arabic numeral at the top of the column, 30 (blue), and the Arabic numeral at the left of the row, 3 (red). XXXIII means 33. Notice that there is no Roman numeral for the value zero.

Sometimes this rule was not followed, so you will see four letters repeated in succession, such as IIII for four or MCCCC for one thousand four hundred.

Fragments of the Roman system of numerals survive in modern times, as in the expression "C note" meaning a one hundred dollar bank bill.

Numerals 1 to 99
I=1, V=5, X=10, L=50, and C=100

	.	10	20	30	40	50	60	70	80	90
0	.	X	XX	XXX	XL	L	LX	LXX	LXXX	XC
1	I	XI	XXI	XXXI	XLI	LI	LXI	LXXI	LXXXI	XCI
2	II	XII	XXII	XXXII	XLII	LII	LXII	LXXII	LXXXII	XCII
3	III	XIII	XXIII	XXXIII	XLIII	LIII	LXIII	LXXIII	LXXXIII	XCIII
4	IV	XIV	XXIV	XXXIV	XLIV	LIV	LXIV	LXXIV	LXXXIV	XCIV
5	V	XV	XXV	XXXV	XLV	LV	LXV	LXXV	LXXXV	XCV
6	VI	XVI	XXVI	XXXVI	XLVI	LVI	LXVI	LXXVI	LXXXVI	XCVI
7	VII	XVII	XXVII	XXXVII	XLVII	LVII	LXVII	LXXVII	LXXXVII	XCVII
8	VIII	XVIII	XXVIII	XXXVIII	XLVIII	LVIII	LXVIII	LXXVIII	LXXXVIII	XCVIII
9	IX	XIX	XXIX	XXXIX	XLIX	LIX	LXIX	LXXIX	LXXXIX	XCIX

Numerals 100 to 2,999
C=100, D=500, and M=1000

To create numbers in the 101 to 2,999, concatenate the following letters with the appropriate letters from the chart above.

100	200	300	400	500	600	700	800	900	1000	2000
C	CC	CCC	CD	D	DC	DCC	DCCC	CM	M	MM

Examples

1. DCCCLXIX
DCCC LX IX (break into levels of 1000s, 100s, 10s, and 1s)
DCCC means 800
LX means 60
IX means 9

800+60+9=869

1. CMLXIV
CM LX IV (break into levels of 1000s, 100s, 10s, and 1s)
CM means 900
LX means 60
IV means 4

900+60+4=964

3. On the title page of a book is given the date

MDCCCLXXXVI

M DCC LXXX VI (break into levels of 1000s, 100s, 10s, and 1s)
M means 1,000
DCCC means 800
LXXX means 80
VI means 6

1,000+800+80+6=1,886 or the year 1886

Handy Roman Numeral Converter
At Nova Roma you will find the Handy Roman Numeral Converter, which I used to verify the information on this page.