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Roman Numerals

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Date: 06/05/97 at 09:08:16
From: e eddy
Subject: Roman numerals

Is there a reference table for writing Roman numerals? If so, what is
it? If not, how does one write one million and ten thousand in Roman
numerals?

I have looked in math books, the dictionary, and searched the
Internet. Most of the Internet search has turned up information on
lot of time.

A student asked me this question. I am using this search as a teaching
tool to show students how to get information on the internet. This is
a great web site. I plan to share it with others at my school.
```

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Date: 06/05/97 at 15:12:16
From: Doctor Jodi
Subject: Re: Roman numerals

Hi there!

This is a great question. Here's what I found at the AskERIC site:

http://ericir.syr.edu/Virtual/Lessons/Mathematics/Probability/PRB0006.html

BACKGROUND:

Roman numerals were developed around 500 B.C. at least partially from
primitive Greek alphabet symbols which were not incorporated into

The symbol "I" for 1 was derived from one finger. Five fingers held up
indicated five of whatever was being counted.  The "V" then was the
hand outstretched vertically with the space between the thumb and
first finger forming the "V".

Originally the Greek letter "X", or "chi", meant 50, but in monument
transcriptions it is easy to trace the original symbol's change to
"L", and "X" came to mean 10.  Another theory for "X" is that ten 1's
were written in a row, and then crossed out with an "X" to simplify
counting.  Then the "X" alone became a shorthand version of 10.  Yet
another idea is that "V" looks like the top half of "X", as 5 is half
of 10. Other scholars think that "V" doubled with an upside-down "V"
meant 5 times 2, or "X".  "C", indicating 100, came from the Latin
word "centum", a hundred. (Also century, centennial, etc.)  "M" is
from "mille", a thousand. Larger numbers, like 5,000, are shown by
putting a small bar called a "vinculum" above the "V" symbol,
indicating multiplication by 1,000.

Until fairly recently a commonly used Roman numeral for 1,000 was "CI
backwards C", derived from the Greek "phi", or "I" superimposed on
"O". Half of this symbol, "I backwards C", led to "D" for 500, half
of 1,000.

Generally, decoding Roman numerals is very straightforward.  The
largest numeral is at the left, with descending numerals moving to the
right.  Numbers are added as you go, as seen in these examples:

CCLXVII: 200 + 50 + 10 + 5 + 1 + 1 = 267

MMMCCLXXXI: 1,000 + 1,000 + 1,000 + 100 + 100 + 50 + 10 + 10 + 10 + 1
= 3,281

DCCXVII: 500 + 100 + 100 + 10 + 5 + 1 + 1 = 717

Rather than continuing to add 1's to make 4 ("IIII") or 9 ("VIIII"),
subtraction was included in the computation of the numerals to
simplify and shorten the resulting numbers.  Therefore, 4 is shown
"IV", or 5 minus 1.  The smaller numeral BEFORE the larger one means
subtract.  "IX" is 9, or 10 minus 1.  40 is "XL", 50 minus 10; 90 is
"XC", 100 minus 10; "CD" is 400, or 500 minus 100; and "CM" is 900, or
1,000 minus 100. Students can follow the principle that subtraction
takes place ONLY when the smaller numeral is before the larger one,
and involves 4 and 9 in various place values.

Obviously, the cumbersome aspect of Roman numerals is one of the main
reasons that they have been replaced by the Arabic system in our daily
mathematical lives. Roman numerals remain important as a part of the
world's cultural past, and a unique way to express numbers.

REFERENCES:

Most encyclopedias have at least some information on Roman numerals,
and several books on Roman numerals are appropriate for students.
Three suggestions:

_Number Art - Thirteen 1 2 3's from around the world_, by Leonard
sophisticated overview of world numerical systems.

_Signs and Symbols Around the World_, by Elizabeth Helfman, published
by Lothrop, Lee and Shepard Co, NY, has a chapter on numerals of many
cultures. There is a very short section on Roman numerals, but a great
deal of general information about counting and mathematics
applications throughout the world.

NY, is a much simpler book, but suitable for younger students.

-Doctor Jodi,  The Math Forum
Check out our web site!  http://mathforum.org/dr.math/
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