the Roman letters used as numerals until the 10th cent. a.d.: in Roman numerals I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, and M = 1,000
Other numbers are formed from these by adding or subtracting: the value of a symbol following another of the same or greater value is added (e.g., III = 3, XV = 15); the value of a symbol preceding one of greater value is subtracted
(e.g., IX = 9); and the value of a symbol standing between two of greater value is subtracted from that of the second, the remainder being added to that of the first (e.g., XIX = 19)Roman numerals are commonly written in capitals, though they may be written in lowercase
letters, as in numbering subdivisions (e.g., Act IV, scene iii) A bar over a letter
indicates multiplication by 1,000 (e.g., 57472 = 5,000)
Webster’s New World College Dictionary, Fourth Edition, compiled by the
editors of Webster’s New World Dictionaries. Copyright © 2010 by Houghton
Mifflin Harcourt. Published by Houghton Mifflin Harcourt. All rights reserved.