Write these notes in your spirals!
 Are expressed by letters of the alphabet.
 I=1
 I
 V=5
 Value
 X = 10
 Xylophones
 L = 50
 Like
 C = 100
 Cows
 D = 500
 Do
 M = 1000
 Milk
1. A letter repeats its value as many times
as it appears
X = 10
XX= 20
XXX= 30
 BUT…
 Values can only repeat 3 times
 The “fives” (V, L, D) do NOT repeat
2. If one or more letters are placed after
letters of greater value, add the values
together.
 VI = 6 (5 +1)
 MC = 1100 (1000+100)
3. If a letter is placed before a letter of
greater value, subtract that amount
 IV = 4 (5-1)
 IX = 9 (10-1)
 CD = 400 (500-100)
XL = 40 (50-10)
XC = 90 (100-10)
CM=900 (1000-100)
THESE ARE THE ONLY “LEGAL” SUBTRACTION PAIRS!
4. Except for the “legal” subtraction pairs,
Roman numerals descend in value
from left to right.
 MMDCCLXVI = 2766 (1000 + 1000 + 500 +
100 + 100 + 50 + 10 + 5 + 1)
 MCMXCIX = 1999 [1000+(1000-100)+(10010)+(10-1)]