What are Roman numerals and what do they mean?

Answer 1

Roman Numerals

The use of Roman Numerals in the English Language is a relic of the Roman Empire, in particular the Roman occupation of Britain which lasted for about 500 years up to around the year 450 AD.

They are mostly used nowadays for naming monarchs and other nobility, for family names where there is a tradition of using the same first name from one generation to the next, and on clock faces.

The symbols themselves are quite simple, but their use in actual numbers can be a little tricky.

The symbols are:

I - 1;

V = 5;

X = 10,

L = 50;

C = 100;

D = 500;

M = 1000

The general rule is that placing a lower number to the left of a higher one subtracts the lower number and placing a lower number to the right adds the lower number.

Some examples to show how this works:

I = 1

II = 2

III = 3

IV = 4 that is five (V) minus 1 (I to the left) ("IIII" is sometimes used on clocks for 4)

V = 5

VI = 6 that is five (V) plus 1 (I to the right)

VII = 7

VIII = 8

IX = 9, that is 10 (X) minus 1 (I to the left)

X = 10

XI = 11

XII = 12

XIII = 13

and now a tricky one -

XIV = 14 that is X for 10 plus IV for 4!

XV = 15

XVI = 16

XVII = 17

XVIII = 18

then another tricky one

XIX = 19 that is the first X is ten plus IX (to the right) for 9

XX = 20

The pattern continues XXX = 30 until

XL = 40 that is L (50) minus 10 (the X to the left)

XLI = 41, XLII = 42 etc.

This goes on up to LXXX = 80 (L = 50 plus XXX = 30 to the right) and then it goes

XC = 90 that is C (100) minus 10 (the X to the left)

Again this goes on CC = 200, CCC = 300 but

CD is 400, again D (500) minus C (100) to the left.

This pattern continues DC = 600, DCC = 700 DCCC - 800 but, this time as expected (!)

CM is 900 that is M (1000) minus the C (100) on the left.

The year 2008 is MMVIII made up of two "M" s (2000) plus VIII on the right.

Many movies and TV shows use Roman Numerals for their copyright dates, which is a tradition from the earliest motion pictures.

Another answer:

Roman Numerals are what Romans used to use for numbers. Different symbols have different numeral values. For example, I = 1, V = 5, and X = 10. When these symbols are combined in different ways the other numbers are formed. There are several rules for the placement of the symbols.

1. You may place up to 3 of the same symbol adjacent to each other to indicate addition. For example: I = 1; II = 1+1 = 2; III = 1+1+1 = 3. Note that IIII is not proper because you may have no more than 3 of the same symbol in a row.
2. You may place a smaller symbol after a larger one to indicate addition. For example: V = 5; VI = 5+1 = 6; VII = 5+1+1 = 7; VIII = 5+1+1+1 = 8. Again VIIII would not be proper because there are 4 Is immediately adjacent to each other.
3. You may place a smaller symbol immediately before a larger symbol to indicate subtraction. For example IV = 5-1 = 4; IX = 10-1 = 9.
   

The basic numerals are:

I = 1

V = 5

X = 10

L = 50

C = 100

D = 500

M = 1000

Some examples of correct Roman Numerals:

III = 1 + 1 + 1 = 3

IX = 10 - 1 = 9

XIV = 10 + 5 - 1 = 14

XXXII = 10 + 10 + 10 + 1 + 1 = 32

LXIX = 50 + 10 + 10 - 1 = 69

MMVIII = 1000 + 1000 + 5 + 1 + 1 + 1 = 2008

MMIX = 1000 + 1000 + 10 - 1 = 2009

(Numbers larger than 1000 could be indicated by a bar across the top, indicating 1000 times the value.)