OK, here is the best Mnemonic: Sentence to remember Roman Numerals I fished out from the Google Ocean. I only made a few changes to fit in my blog format.
The ascending order of Roman numerals: LCDM:
Lucky Cows Drink Milk
Lucy Can't Drink Milk
The Roman numerals in order for I, V, X (1, 5, 10)
I Vant XRays
The Roman numerals in order for I V X L C D M (1 5 10 50 100 500 1000)
I Value Xylophones Like Cows Dig Milk
A Poem to remember all the Roman numerals:
M's "mille" (or 1000 said)
D's half (500 - quickly read!)
C's just a 100 (century!)
and L is half again - 50!
So all that's left is X and V
(or 10 and 5) - and I - easy!
Explanation Roman Numerals
| I | = | 1 |
| V | = | 5 |
| X | = | 10 |
| L | = | 50 |
| C | = | 100 |
| D | = | 500 |
| M | = | 1000 |
Roman numerals are expressed by letters of the alphabet and are rarely used today except for formality or variety. There are four basic principles for reading Roman numerals:
- A letter repeated once or twice repeats its value that many times (XXX = 30, CC = 200, etc.).
- One or more letters placed after another letter of greater value increases the greater value by the amount of the smaller (VI = 6, LXX = 70, MCC = 1200, etc.).
- A letter placed before another letter of greater value decreases the greater value by the amount of the smaller (IV = 4, XC = 90, CM = 900, etc.). Several rules apply for subtraction: (a) only subtract powers of ten (I, X, or C, but not V or L); (b) only subtract one number from another; (c) do not subtract a number from one that is more than 10 times greater (that is, you can subtract 1 from 10 [IX] but not from 20—there is no such number as IXX).
- A bar placed on top of a letter or string of letters increases the numeral's value by 1,000 times (XV = 15,
= 15,000).
