Roman numerals are expressed by letters of the alphabet:

        I=1   V=5    X=10   L=50   C=100   D=500M=1000   

          There are three basic principles for reading and writing Roman numerals:

        1. A letter repeats its value that many times (XXX = 30, CC = 200, etc.). A letter can only be repeated three times.
                                                                              
        2. If one or more letters are placed after another letter of greater value, add that amount.
             VI = 6 (5 + 1 = 6)
             LXX = 70 (50 + 10 + 10 = 70)
             MCC = 1200 (1000 + 100 + 100 = 1200)

 3. If a letter is placed before another letter of greater value, subtract that amount.

             IV = 4 (5 – 1 = 4)
             XC = 90 (100 – 10 = 90)
             CM = 900 (1000 – 100 = 900)

        Several rules apply for subtracting amounts from Roman numerals:

        a. Only subtract powers of ten (I, X, or C, but not V or L) 
            For 95, do NOT write VC (100 – 5).
            DO write XCV (XC + V or 90 + 5)

        b. Only subtract one number from another.
            For 13, do NOT write IIXV (15 – 1 - 1).
            DO write XIII (X + I + I + I or 10 + 3)

         c. Do not subtract a number from one that is more than 10 times greater
             (that is, you can subtract 1 from 10 [IX] but not 1 from 20—there is no such number as IXX.)
             For 99, do NOT write IC (C – I or 100 - 1).   DO write XCIX (XC + IX or 90 + 9)

    

ROMAN NUMERAL CHART

EXAMPLES OF ROMAN NUMERALS IN EVERYDAY LIFE