What is the standard number for roman numerals mdcclxxxix?

Answer 1

1789

Let's break it down. I prefer upper case.

First, M = 1000, D = 500, C = 100, L = 50, X = 10, V = 5 (not used in this one)

and I = 1

If the smaller number is left of the larger number, the smaller is subtracted

from the larger (ix or IX = 10 -1 = 9). If the smaller is right of the larger, add.

M D C C L X X X I X

only the last 2 (IX) have a smaller before a larger, so IX = 9, then the rest is added:

1000 + 500 + 100 + 100 + 50 + 10 + 10 + 10 + (9) = 1789