Wednesday, May 25, 2011

How to read and write in roman numerals.

Unless you've made a point in your life to figure out how to read and write in roman numerals beyond 12 (XII), you probably won't be able to know what MMXI means. In case you're wondering, it means 2011. 

I've learned how to read and write most from playing Nancy Drew games. Several of which involve roman numerals to solve puzzles. It may not seem all that hard, but in a world where the use of these unquie letters and means are rapidly disappearing, figuring out the meaning beyond XII is hard. 

Most people only know roman numerals up to XII. So let's refresh our basic knowledge of these letters. 
I- 1
II- 2
III- 3
IV- 4
V- 5
V1- 6
VII- 7
IX- 9 
X- 10
XI- 11
XII- 12

Now that we've refreshed our memories, I've decided to give you a crash course in the reading and writing of roman numerals. Fun, right?

Lets keep in mind the four basic rules. 
1. A letter repeats its value that many times (XXX = 30, CC = 200, etc.). A letter can only be repeated three times.
2. If one or more letters are placed after another letter of greater value, add that amount.
VI = 6 (5 + 1 = 6)
LXX = 70 (50 + 10 + 10 = 70)
MCC = 1200 (1000 + 100 + 100 = 1200)

3. If a letter is placed before another letter of greater value, subtract that amount.
    IV = 4 (5 – 1 = 4)
    XC = 90 (100 – 10 = 90)
    CM = 900 (1000 – 100 = 900)
    Several rules apply for subtracting amounts from Roman numerals:
    • a. Only subtract powers of ten (I, X, or C, but not V or L)
      For 95, do NOT write VC (100 – 5).
      DO write XCV (XC + V or 90 + 5)
    • b. Only subtract one number from another.
      For 13, do NOT write IIXV (15 – 1 - 1).
      DO write XIII (X + I + I + I or 10 + 3)
    • 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 1 from 20—there is no such number as IXX.)
      For 99, do NOT write IC (C – I or 100 - 1).
      DO write XCIX (XC + IX or 90 + 9)
      4. A bar placed on top of a letter or string of letters increases the numeral's value by 1,000 times.

      XV = 15, (X-bar)(V-bar)= 15,000
I found these handy tips at I hope it was helpful!

What the symbols mean:
I- 1
L- 50
C- 100
D- 500
M- 1000

Roman Numerals go in an alternating system of fives and tens.

Anyways, as I was saying earlier, roman numerals are dying out. What was once used every where can now only be found in a few places in every day life. The most common examples are seen on watches and in titles (Ex. Queen Elizabeth II). I think that this is an important form of number system that should be preserved. That, along with cursive writing. (But that's a different post!)

Personally, I love using roman numerals, although I'll admit I have trouble figuring out how to write dates and such in them. It's confusing, but fun. 

Interesting dates in roman numerals:
MCM- 1900, the turn of the 20th century
MCMXIV- 1914, the start of WWI 
MCMXVII- 1917, China declares war on Germany
MCMXXXII- 1932, Franklin Delano Roosvelt is elected president of the United States
MCMXLI- 1941, Japan moves it's forces into french indochina
(There's a reason why I'm using examples from the early L (50) years of the 1900s).

So, do you think we should preserve roman numerals? Do you ever use them? What are some other examples of roman numerals besides the ones I mentioned? But about cursive writing? Do you write in cursive or do you print? 



  1. great...
    i just want to share roman numeral web from other link..

    1. Hey thanks so much for the link! :D Its always great to see new resources.


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