BIO 190—Scientific Communication I

Understanding Roman Numerals

Visit Yahoo! to see other accounts of Roman numerals

Over two thousand years ago, the ancient Romans adapted the Etruscan way of writing numbers by using letters of their own alphabet (the Etruscans had in turn based their system on that used by the Greeks). The resulting numerals are very cumbersome to work with, and today the numbers in common use are modeled on those developed by the Arabs over a thousand years ago from numerals developed in India. You don’t see Roman numerals much any more except in outline numbering, although until about twenty or thirty years ago, the year of copyright in a book was sometimes in Roman numerals.

There was a lot of variation in the use of Roman numerals by the Romans, but beginning in the Middle Ages, the numerals, like the Latin language, became formalized, giving us the system used today.

Below is a chart showing some conversions between Arabic and Roman numerals. To make a Roman numeral not on the chart, just string together the parts: 475 would be 400 (CD) followed by 70 (LXX) followed by 5 (V), CDLXXV.

1	I	10	X	100	C
2	II	20	XX	200	CC
3	III	30	XXX	300	CCC
4	IV	40	XL	400	CD
5	V	50	L	500	D
6	VI	60	LX	600	DC
7	VII	70	LXX	700	DCC
8	VIII	80	LXXX	800	DCCC
9	IX	90	XC	900	CM
10	X	100	C	1000	M
11	XI	110	CX	1100	MC
12	XII	120	CXX	1200	MCC
13	XIII	130	CXXX	1300	MCCC
14	XIV	140	CXL	1400	MCD
15	XV	150	CL	1500	MD
16	XVI	160	CLX	1600	MDC
17	XVII	170	CLXX	1700	MDCC
18	XVIII	180	CLXXX	1800	MDCCC
19	XIX	190	CXC	1900	MCM
20	XX	200	CC	2000	MM

Here are modern European, Arabic, and Persian numerals; all three developed from an older style that the Arabs adopted from India (and to which they added zero). On some computer systems you may see empty boxes instead of the Arabic and Persian examples.

European	0	1	2	3	4	5	6	7	8	9
Arabic	٠	١	٢	٣	٤	٥	٦	٧	٨	٩
Persian	۰	۱	۲	۳	۴	۵	۶	۷	۸	۹

Citation: Clark, Curtis. 2001. BIO 190 - Understanding Roman Numerals. California State Polytechnic University, Pomona, http://www.csupomona.edu/~jcclark/classes/bio190/mm.html.

Table of Contents

These are official class materials of BIO 190 as taught at California State Polytechnic University, Pomona, by Curtis Clark. They are subject to change without notice to anyone but students currently enrolled in the class.