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### Converting from Hindu-Arabic Numerals to Roman Numerals

```
Date: 05/18/99 at 14:59:06
From: Debbie Whittington
Subject: Roman Numerals

I need to know the conversion for Roman numerals from our number
system. I have searched in my local library, and on the Internet, but
I can't seem to find an anwser.
Thanks, littledeb.
```

```
Date: 05/18/99 at 16:43:27
From: Doctor Rick
Subject: Re: Roman Numerals

Hi, Debbie,

Here is how I convert our Hindu-Arabic numerals to Roman numerals.

Convert one digit at a time. Each digit is converted the same way,
except that the symbols are different:

1s digit: I for 1, V for 5
10s digit: X for 1 (10), L for 5 (50)
100s digit: C for 1 (100), D for 5 (500)
1000s digit: M for 1 (1000), nothing for 5 (5000) -- see below.

These are the conversions for each digit:

1000s         100s          10s           1s
--------------------------------------------------
0 = nothing  0 = nothing  0 = nothing  0 = nothing
1 = M        1 = C        1 = X        1 = I
2 = MM       2 = CC       2 = XX       2 = II
3 = MMM      3 = CCC      3 = XXX      3 = III
4 = MMMM     4 = CD       4 = XL       4 = IV
5 = nothing  5 = D        5 = L        5 = V
6 = nothing  6 = DC       6 = LX       6 = VI
7 = nothing  7 = DCC      7 = LXX      7 = VII
8 = nothing  8 = DCCC     8 = LXXX     8 = VIII
9 = nothing  9 = CM       9 = XC       9 = IX

Put the symbols from each digit together in the same order as they
were in our (Hindu-Arabic) numeral system -- from left to right,
largest to smallest.

For example, let's convert 1999:

1000 => M
900 =>  CM
90 =>    XC
9 =>      IX
-------
MCMXCIX

Notice that the system I just described only goes up to 4,999.
Actually, sometimes you will see a symbol with a bar over it to
represent 1000 times the usual value of a symbol. Thus,
_           _             _
V = 5000    X = 10,000    L = 50,000    ...

But I think it's unconventional to have symbols with bars to the right
of symbols without, or to intersperse them, as in
_           _ _
4000 = MV    9000 = VMV

Instead, the barred numbers should be a solid block to the left of the
unbarred numbers. You can write:
_________
3,859,429 = MMMDCCCLV MMMMCDXXIX

news that the rules I just gave you have been broken frequently over
the years -- at these Web sites:

Roman numeral Date Conversion Guide
http://www2.inetdirect.net/~charta/Roman_numerals.html

Roman numerals -- History and Use

- Doctor Rick, The Math Forum
http://mathforum.org/dr.math/
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