ROMAN NUMERALS

The Romans used certain key numbers as base numbers, each represented by a letter of the alphabet:

Arabic number

Roman number

1

I

5

V

10

X

50

L

100

C

500

D

1000

M

I

stands for one finger, II for two fingers, III for three fingers

V

represents the shape made by the thumb and first finger

X

is formed by placing one V on top of another, thus X

C

stands for the Latin word centum ("a hundred")

M

stands for the Latin word mille ("a thousand")

D

is half of M when it is written

There are several theories about L. It may come from the sign ^ used in inscriptions for 50, or it may be half of C when written [ .

 

RULES FOR CALCULATING NUMBERS
  1. When a "smaller" number appears to the right of a "larger" one, the smaller is added to the larger, e.g. VI = V + I (i.e. 6) and CXII C+ X+ I+ I (i.e. 112).
  2. When a "smaller" number appears at the left of a "larger", the smaller is subtracted from the larger, e.g. IV = V - I (i.e. 4) and XC = C - X (i.e. 90).

 

The main problem with the Roman system is that large numbers took up a lot of space. The Arabic system avoids this by having the symbol 0. The same digits can have the same value since it is their position which shows whether they are units, tens, hundreds, thousands etc. Compare the Arabic 33, 303 and 3033 with Roman XXXIII, CCCIII and MMMXXXIII.

The Roman system is still used today. Roman numerals are often used to number chapters or paragraphs in books etc. (as above), and on clock faces, buildings and monuments. The copyright date of television programmes is given in this way too, e.g. Ó MCMXCVI means that the programme first appeared in 1996.

What are these numbers in Arabic?

XV

XX

XIX

CL

XL

XIV

LXVII

LX

XVI

MCMLXXXVI

MLXVI

MCDXCII