repeated is NOT repeated. For example, VV is NOT used for 10 (5+5) because X is 10
and LL is NOT used for 100 (50+50) because C = 100).
c. Smaller Numerals Before Larger. When a smaller numeral placed before a
larger one, the smaller value is subtracted from the larger one. Only one number can
be subtracted in this way. Thus, IV (5 - 1) = 4; IX (10 - 1) = 9; and XC (100 - 10) = 90
are correct, but 3 is never written IIV.
d. Smaller Numerals After Larger. A smaller numeral placed after a larger one
is added to the larger number. For example, VIII = (5+3) = 8 ; XIII = (10+3) = 13; CLX =
(100+50+10) = 160.
e. Smaller Numeral Between Two Larger. A smaller numeral between two
larger ones is ALWAYS subtracted from the larger numeral which follows it as CXL (100
+ [50-10]) = 140; MCMLXXVI (1000 + [1000-100] + 50 + 10 + 10 + 5 + 1) = 1976.
f. The Use of "j." As a precaution against error, the last "i" may be replaced by
a "j." When this method is used, 3 would be written as iij.
g. Table of Roman Numerals. Table 1-6 shows examples of Roman numerals
and their equivalents.
ss
=
1/2
x
=
10
xx
=
20
li
=
51
i
=
1
xi
=
11
xxi
=
21
lix
=
59
ii
=
2
xii
=
12
xxii
=
22
lx
=
60
iii
=
3
xiii
=
13
xxiii
=
23
lxx
=
70
iv
=
4
xiv
=
14
xxiv
=
24
lxxx
=
80
v
=
5
xv
=
15
xxv
=
25
xc
=
90
vi
=
6
xvi
=
16
xxvi
=
26
c
=
100
vii
=
7
xvii
=
17
xxvii
=
27
ci
=
101
vii
=
8
xviii
=
18
xxviii
=
28
cxxi
=
121
ix
=
9
xix
=
19
xxix
=
29
d
=
500
m
=
1000
Table 1-6. Examples of Roman numerals.
h. Number After Modified Noun. When a number expressed in Roman
numerals is used to modify a noun, the number follows the noun. The noun is likely to
be a unit of the apothecary system or a unit of dosage. For example, "gr ii" would be
interpreted as "two grains" and "caps i" would mean "one capsule."
MD0913
1-6