
Roman Numerals
Roman numerals are a number system from ancient Rome. Most everyone knows of them; Perhaps you've seen them on a clock, a super bowl ring or have a friend with a generational suffix. Although it seems like they should be obsolete, they are still used in modern times more than you may think.
Roman numerals are also used in Pharmacy by practitioners on prescription drug orders and on packaging to designate DEA schedules for controlled substances.
Here they are translated into our modern system:
I  1  One  V  5  Five  X  10  Ten  L  50  Fifty  C  100  One Hundred  D  500  Five Hundred  M  1,000  One Thousand  SS  1/2  Half 
Rules of use for Roman Numerals
RULE #1
If one or more letters are placed after another letter of greater value, add that amount.
Example: X V I = (10 +5 +1)
RULE #2
If a letter of lower value is placed before another letter of greater value, the lower value is subtracted from the higher value.
Example: I X = (10  1)
RULE #3
First look for and do the subtractions, then add together the remaining values.
Example: C L X I V
Subtractions first  = C L X + (I V)  Add remaining values  = C L X + (4)  Translated  = 100+50+10+(4)  Answer  = 164 
RULE #4
A letter can only repeat three times.
For example the number 8 is VIII, and the number 9 is IX. (Not VIIII)
Another example: the number 30 is XXX, and 40 is XL. (Not XXXX)
RULE #5
V, L and D are never subtracted or repeated.
TRY SOME:
X V I I I  =  10+5+3 = 18  X I V  =  10+(51)= 14  L X I I I  =  50+10+3 = 63  C X V I I I  =  100+10++5+3 = 118  L X I V  =  50+10+(51) = 64  M C M X V I  =  1000+(1000100)+10+5+1 = 1916 
TO SEE THE ANSWERS, HIGHLIGHT THE ANSWER COLUMNS.
Some thoughts on Roman Numerals  editorial.
Don't overthink them. They are very simple and closely guided by the rules. When you're first learning them, do yourself a favor and don't try to convert numbers into Roman numerals. Concentrate initially on tearing apart roman numerals into normal numbers. Lastly, don't try to master them immediately as you likely won't see the larger ones often.
Where would you like to go now?
Back to Math Homepage
Back to Homepage
Site Map
Roman Numerals  top of page

