The usual way to write nines in Roman numerals is IX and not VIIII. Curiously, with 900 it is common to see it written as MDCCCC, for example in the picture below (I first noticed it in my step-father’s diploma from Harvard). Nevertheless one also often sees MCM, for example in the opening credits of movies. What’s the difference, and why do so many choose the to me ugly MDCCCC?

enter image description here

  • 1
    You probably want to change 900 to 1900. I tried to edit this days ago but the moderators haven't gotten to reviewing it
    – C Monsour
    Commented Jan 3, 2020 at 1:18

2 Answers 2


Here is a picture from The Inland Paper (volume 24) [that you can find here].

Since the paper was to be published in 1900, the editors were asked to provide their opinion on the writing of the number of that year in Roman numerals:

Choice comes between MCM and MDCCCC. Regular process of economy in such notation indicates MCM as decidedly preferable. At each place in the series where addition of characters may be avoided by changing to expression by subtraction, the change is made.

Here the difference is all a matter of economy, since both the notations are exceptionally allowed.

The Pupils' Arithmetic (James Charles Byrnes, Julia Richman, John Storm Roberts, Macmillan, 1917) says instead that the Romans preferred to write MDCCCC.

Now it is probably a matter of choice, or convenience. No one really knows the true reasons why the two writings became alternative to each other.

There's a similar problem on the writing of the Roman 4: IV or IIII? Some analog clocks prefer the second, and there are bunches of hypothesis and tales about the motives. We won't treat them, instead I leave to you this eloquent article!


Mdcccc is correct

IIV is correct

People shorten things but the long form is always the most correct.

  • MDCCCC rather ?
    – Quidam
    Commented Dec 28, 2019 at 22:11
  • Welcome to the site! Please consider registering your account and taking a look at our introductory tour. On the answer itself: Did you mean IIX instead of IIV? Abbreviation from VIII makes more sense than from III to me.
    – Joonas Ilmavirta
    Commented Dec 29, 2019 at 20:39

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