section_path: Description/Other forms/Other additive forms
section_name: Other additive forms
paragraph_text: Other additive forms
  
  While subtractive notation for 4, 40, and 400 (IV, XL, and CD) has been the usual form since Roman times, additive notation to represent these numbers (IIII, XXXX, and CCCC) very frequently continued to be used, including in compound numbers like 24 (XXIIII), 74 (LXXIIII), and 490 (CCCCLXXXX). The additive forms for 9, 90, and 900 (VIIII, LXXXX, and DCCCC) have also been used, although less often.
  
  The two conventions could be mixed in the same document or inscription, even in the same numeral. For example, on the numbered gates to the Colosseum, IIII is systematically used instead of IV, but subtractive notation is used for XL; consequently, gate 44 is labelled XLIIII.
  
  Especially on tombstones and other funerary inscriptions, 5 and 50 have been occasionally written IIIII and XXXXX instead of V and L, and there are instances such as IIIIII and XXXXXX rather than VI or LX.
  
  Modern clock faces that use Roman numerals still very often use IIII for four o'clock but IX for nine o'clock, a practice that goes back to very early clocks such as the Wells Cathedral clock of the late 14th century. However, this is far from universal: for example, the clock on the Palace of Westminster tower (commonly known as Big Ben) uses a subtractive IV for 4 o'clock.
  
  Several monumental inscriptions created in the early 20th century use variant forms for "1900" (usually written MCM). These vary from MDCCCCX for 1910 as seen on Admiralty Arch, London, to the more unusual, if not unique MDCDIII for 1903, on the north entrance to the Saint Louis Art Museum.