[OT] Roman numeral arithmetic (was: Re: [lojban] (from lojban-beginners) pi'e)

From: DougEwell2@cs.com
Date: Sat Sep 22 2001 - 18:46:36 EDT


In a message dated 2001-09-22 11:35:16 Pacific Daylight Time,
jameskass@worldnet.att.net writes:

>> I would be fascinated to see some sort of evidence that addition and
>> subtraction is easier in Roman numerals than in Hindu-Arabic ("European")
>> numerals.
>
> I + I = II
> X + X = XX
> X + X + X = XXX
> C + X = CX
> CX - X = C

For these carefully chosen examples, sure, but what about:

III + IX = XII
XXIV + XXVII = LI
C - I = XCIX

etc. This is no better than European digits, and it feels a little like
doing math with pounds, shillings, and pence.

In a message dated 2001-09-22 11:59:22 Pacific Daylight Time,
ruland@netcologne.de writes:

> Addition and subtraction definitely isn't easier in Roman numerals that in
> Hindu-Arabic numerals. As I understood Edward's words, addition and
> subtraction is easier *than multiplication and division* in Roman numerals.

Edward's words were originally as follows (whole paragraph this time, to
avoiding quoting out of context):

> We generally believe that the mathematicians led by Leonardo Fibonacci won
> out over the Old Guard in replacing Roman numerals with Hindu-Arabic
> numerals, but the victory was long drawn out, and is still incomplete.
> Businesses continued to use Roman numerals for several centuries (because
> addition and subtraction is easier in Roman numerals, and they didn't have
> that much call for multiplication and division until interest became
> socially acceptable). In Fibonacci's time, and up until the 17th century,
> clocks existed almost exclusively in churches and monasteries, where they
> regulated the hours of prayer. The Catholic church was having nothing to do
> with these new-fangled heathen numbers, especially since the Crusades were
> on at the time, and continued for centuries. The Church was especially
> opposed to the idea of zero, both as the work of the infidel, and on
> Aristotelian grounds. That is why the the twelve-hour system starts at XII,
> followed by I, and not 0:00:00.

Reading it again, I still wouldn't have interpreted the passage about
"addition and subtraction is easier..." to mean "... than multiplication or
division," but obviously this is true (also for European numerals, but less
so than for Roman numerals).

In any case I am scratching my head as to how this ended up on the Unicode
list, unless it was somehow seen as relevant to the earlier discussion about
sorting text that contains both European and Arabic-Indic digits.

-Doug Ewell
 Fullerton, California



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