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Roman Numerals

roman mcmix

Ancient Romans used a special method of showing numbers

Examples: They wrote C instead of 100
And wrote IX instead of 9

Read on to learn about Roman Numerals or go straight to the Roman Numeral Conversion Tool.

The Roman Symbols

Romans Numerals are based on the following symbols:

1 5 10 50 100 500 1000
I
V
X
L
C
D
M

Basic Combinations

Which can be combined like this:

1 2 3 4 5 6 7 8 9
I
II
III
IV
V
VI
VII
VIII
IX


10 20 30 40 50 60 70 80 90
X
XX
XXX
XL
L
LX
LXX
LXXX
XC


100 200 300 400 500 600 700 800 900
C
CC
CCC
CD
D
DC
DCC
DCCC
CM

Forming Numbers - The Rules

When a symbol appears after a larger (or equal) symbol it is added

  • Example: VI = V + I = 5 + 1 = 6
  • Example: LXX = L + X + X = 50 + 10 + 10 = 70

But if the symbol appears before a larger symbol it is subtracted

  • Example: IV = V − I = 5 − 1 = 4
  • Example: IX = X − I = 10 − 1 = 9

To Remember: After Larger is Added

Don't use the same symbol more than three times in a row (but IIII is sometimes used for 4, particularly on clocks)

How to Convert to Roman Numerals

Break the number into Thousands, Hundreds, Tens and Ones, and write down each in turn.

Example: Convert 1984 to Roman Numerals.

roman 1984

Break 1984 into 1000,900, 80 and 4, then do each conversion

  • 1000 = M
  • 900 = CM
  • 80 = LXXX
  • 4 = IV

1000 + 900 + 80 + 4 = 1984, so 1984 = MCMLXXXIV

roman medical xavier

How To Remember

Think "MeDiCaL XaVIer".
It has the roman numerals in descending order from 1000 to 1.

I, for one, like Roman numerals!

Really Big Numbers

Numbers greater than 1,000 are formed by placing a dash over the symbol, meaning "times 1,000", but these are not commonly used:

5,000
10,000
50,000
100,000
500,000
1,000,000
V
X
L
C
D
M

Conversion Tool

You can convert to/from Roman Numerals here:

numbers/images/roman.js

 

375, 2034, 2035, 2036, 2037, 2038, 2039, 5113, 5114, 5115
Decimal Numbers