How To Interpret & Write Roman Numerals
Sometimes we'll see roman numerals on compounding formulas and prescriptions or even on sig codes / pharmacy abbreviations (click here to see these sig codes.)
- Start from left to right.
- When a larger roman numeral comes after a smaller one, subtract them.
- Subtracting more than one pair of numeralsis not allowed.
- V L and D can not be subtracted from larger numerals.
- I can only be subtracted from V or X.
- X can only be subtracted from L or C.
- C can only be subtracted from D or M.
- Perform all relevant subtractions first before adding.
- Add up to 3 identical numerals together when repeated.
- V L and D are never repeated.
- When a smaller roman numeral comes after a larger one add them together.
Let’s look at some examples:
DCCLXXVII = 777
MMXIV = 2014
CCL = 250
CXXV = 125
XXIII = 23
DLX = 560
MCCXXII = 1222
XIX = 19
Try converting the following: