5.25 Roman numerals

Roman numerals are becoming increasingly rare, but they still have the following uses:

  • names of rulers, aristocrats, and the names of ships, racing cars and space vehicles:
    • Charles IV
    • Pius XII
    • Bluenose II
    • Saturn V
  • numbers of volumes, chapters, tables, plates, acts and other divisions of a book or play (now often replaced with Arabic numerals):
    • Psalm XXIII
    • Volume XII
    • Appendix III
    • Act II, Scene iii (act number in upper case, scene number in lower case)
  • Government of Canada Statutes:
    • Schedule IV
    • Part III
  • years, centuries and recurring events of major importance:
    • CMLXLV (in very formal contexts)
    • XIX century (or 19th century)
    • XXIII Olympiad

Do not use ordinal forms (st, nd, th, etc.) with Roman numerals.

Lower-case Roman numerals may be used for page numbers in preliminary matter (preface, foreword, table of contents, etc.), subclauses and subordinate classifications in a series.

Note that a bar over a letter in a Roman numeral multiplies its value by 1000:

  • _
    D = 500 000
  • _
    V = 5000