Heather and Barry Barry and Heather Richards
Family Tree
Roman Numerals Explained


I
The easiest way to note down a number is to make that many marks - little I's.
Thus I means 1, II means 2, III means 3. However, four strokes seemed like too
many....
V
So the Romans moved on to the symbol for 5 - V. Placing I in front of the V —
or placing any smaller number in front of any larger number — indicates
subtraction. So IV means 4. After V comes a series of additions - VI means 6,
VII means 7, VIII means 8.
X
X means 10. But wait — what about 9? Same deal. IX means to subtract I from
X, leaving 9. Numbers in the teens, twenties and thirties follow the same form as
the first set, only with X's indicating the number of tens. So XXXI is 31, and
XXIV is 24.
L
L means 50. Based on what you've learned, I bet you can figure out what 40 is. If
you guessed XL, you're right = 10 subtracted from 50. And thus 60, 70, and 80
are LX, LXX and LXXX.
C
C stands for centum, the Latin word for 100. A centurion led 100 men. We still
use this in words like "century" and "cent." The subtraction rule means 90 is
written as XC. Like the X's and L's, the C's are tacked on to the beginning of
numbers to indicate how many hundreds there are: CCCLXIX is 369.
D
D stands for 500. As you can probably guess by this time, CD means 400. So
CDXLVIII is 448. (See why we switched systems?)
M
M is 1,000. You see a lot of Ms because Roman numerals are used a lot to
indicate dates. For instance, this page was written in the year of Nova Roma's
founding, 1998 CE (Common Era; Christians use AD for Anno Domini, "year of
our Lord"). That year is written as MCMXCVIII. But wait! Nova Roma counts
years from the founding of Rome, ab urbe condita. By that reckoning Nova
Roma was founded in 2751 a.u.c. or MMDCCLI.