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:

I1 - One
V5 - Five
X10 - Ten
L50 - Fifty
C100 - One Hundred
D500 - Five Hundred
M1,000 - One Thousand
SS1/2 - Half

Rules of use for Roman Numerals


If one or more letters are placed after another letter of greater value, add that amount.

Example: X V I = (10 +5 +1)


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)


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


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)


V, L and D are never subtracted or repeated.


X V I I I=10+5+3 = 18
X I V=10+(5-1)= 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+(5-1) = 64
M C M X V I=1000+(1000-100)+10+5+1 = 1916


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.

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