# 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 Arabic Persian 0 1 2 3 4 5 6 7 8 9 ٠ ١ ٢ ٣ ٤ ٥ ٦ ٧ ٨ ٩ 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.

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.

Summer Quarter, 2001