Subtraction Pattern for Roman Numerals

Date: 9/7/95 at 21:30:42
From: Anonymous
Subject: Roman Numeral Rules

Several of my friends and I have gotten into a friendly argument
concerning the rules for Roman Numerals that I think you might be
able to help us with.  The question is,  given that 4 is 'IV' and 
9 is 'IX' and 900 is 'CM', does the subtraction pattern follow for
two numerals more than two 'levels' apart, and can numerals which
represent numbers starting with 5 be subtracted?  For example, would
99 be 'IC', would 450 be 'LD', and would 995 be 'VM'?  This came up
because of a trivia question someone posed about what the year 1995
*should* be in Roman Numerals.  He had hazarded the extremely simple
'MVM'.  Is he right?

-'f

Date: 9/8/95 at 11:28:13
From: Doctor Ken
Subject: Re: Roman Numeral Rules

Hello!

As neat as this system would be, the normal way that people write numbers 
like 995 is not to use the subtraction principle over more than one level.
So for instance, 995 would be CM (for 900) XC (for 90) V(for 5), making
CMXCV.  That's one reason they seem kind of awkward to us.

-Doctor Ken,  The Geometry Forum