St. Cecilia School | Student Reference

Roman Numerals

Base Numerals

Roman Symbol	Name	Arabic Value	Derivation of Roman Figure
I	unus	1	A single digit.
V	quinque	5	Graphic representation of five fingers.
X	decem	10	Symbolizes two hands joined together.
L	quinquaginta	50	Adapted from a Chalcidic sign.
C	centum	100	The first letter of the Roman word for one-hundred.
D	quingenti	500	One half of the Chalcidic sign for one-thousand.
M	mille	1,000	The first letter of the Roman word for one-thousand.

Principles

Roman numerals are expressed by letters of the alphabet and are rarely used today except for formality or variety. There are four basic principles for reading Roman numerals:

A letter repeated once or twice repeats its value that many times (XXX = 30, CC = 200, etc.).
One or more letters placed after another letter of greater value increases the greater value by the amount of the smaller (VI = 6, LXX = 70, MCC = 1200, etc.).
A letter placed before another letter of greater value decreases the greater value by the amount of the smaller (IV = 4, XC = 90, CM = 900, etc.).
A bar placed on top of a letter or string of letters increases the numeral's value by 1,000 times (XV = 15, = 15,000).

Arabic - Roman Equivalents

1	I
2	II
3	III
4	IV
5	V
6	VI
7	VII
8	VIII
9	IX
10	X

11	XI
12	XII
13	XIII
14	XIV
15	XV
16	XVI
17	XVII
18	XVIII
19	XIX
20	XX

21	XXI
22	XXII
23	XXIII
24	XXIV
25	XV
26	XVI
27	XXVII
28	XXVIII
29	XXIX
30	XXX

31	XXXI
40	XL
50	L
60	LX
70	LXX
80	LXXX
90	XC
100	C
101	CI
150	CL

200	CC
300	CCC
400	CD
500	D
600	DC
700	DCC
800	DCCC
900	CM
1,000	M
2,000	MM

5,000
10,000
50,000
100,000
500,000
1,000,000

Top

Base Numerals

Roman Symbol

Name

Arabic Value

Derivation of Roman Figure

Principles

Arabic - Roman Equivalents

Roman
Symbol

Arabic
Value