TITLE: Is MDCDXXXIV a correct roman numeral?
QUESTION [6 upvotes]: A building near my workplace has a very large carved inscription: $MDCDXXXIV$
As it looks like roman numeral, I was trying to see what year it was meant to represent. Logically, I'd think it's 1934, but it should be written $MCMXXXIV$.
Is $MDCD$ a valid replacement for $MCM$, like $IIII$ is a valid one for $IV$ in some circumstances?

REPLY [5 votes]: no. But keep in mind that neither IMM for 1999 is, even if many people use it. The only "official" difference numbers are IV, IX, XL, XC, CD, CM.