A Roman Numeral Question

100(C) - 10(X) + 5(V) - 1(I) = 94
http://en.wikipedia.org/wiki/Roman_numerals
http://www.novaroma.org/via_romana/numbers.html

Thanks so much Region Philbis or your response. I did get that answer but I worked it out in a weird way. It looks like you take the higher number then subtract and add the higher number and then subtract the lower number.
I looked at it and thought OK X is 10 and C is 100, that's 90 plus the I from the V which is four = 94 What is the actual rule for calculating Roman numerals? I've forgotten what we did at school, despite being a maths 1 and 2 student. My real love is words. LOL Give me an example with a longer question plus your workings. If you don't mind and thanks very much.
WendyLou

that's how i worked it out, too.
hellfino why they had such a strange system!

the wikipedia link prolly does a good job of explaining the why's and how's of Roman Numerology...

I've always wondered how they solved simple arithmetic problems, let alone anything mathematically complex, before the Arabic numerals were adopted in Europe. Trying to divide XCVII by III must be a nightmare if you have nothing to convert that to.

Likely I would have been counting pebbles.

I don't pretend to understand the process, but calculations were made on what we would call a checker board, which is why the English treasury was called the exchequer.

My understanding is that the Romans used Roman numerals to write
numbers, but the abacus for actual calculations.

From our friend at the online etymological dictionary:



They may well have used an abacus--i was referring how accounts were kept by the Norman rulers of England. However, i am incorrect that it was a means of calculating using Roman numberals.

By the way, arabic numbers aren't arabic, they come from India. India has produced quite a number of genius mathematicians. I suspect quite a few confidence men, too.

The Roman Engineers tended to use Greek and Babylonian technology (geometry and number theory) for higher level mathematics, as Roman numerals praticality is limited to counting. Even interest and loan calculations (return on investment) can be preformed pretty easily using geometric techniques which the Roman's aquired from Euclid's Elements.

BTW the Greeks and ,by extention, the Romans were aware of the concept of prime and composite numbers which is somewhat opaque to Roman Numerals.

Rap

Yah, I understand all that, rap. Pythagoras, just for example, was way ahead of his time. But my question really is, how can you do any kind of numerological notation with Roman numerals? What did the Greeks use for notation purposes? How could they express the concept of pi in Roman numerals? (Obviously, they could not.)

Greek Numbers were octal--they had munbers for 1 to 9, 10 to 90, 100 to 900 and so on---by extention fractional octal fractions also were known ( 1/10th to 9/10ths, 1/100th to 9/100ths). The lack of zero, was a bit of a problem, but that was addressed using a technique now called Egyptian fractions (eg. 3/4=1/2+1/4, 5/6=1/2+1/3).

Pi is a little harder, but because it wasn't known that pi was irrational so it would be closely approximatd as an improper fraction and many Greek and Roman mathemeticians spent their lives getting closer and closer to Pi (some approximations were good to five decimal places).

In addition Archimedes was so good at these techiniques using the processes of Zeno (infintesimals) to determine the volumn of a sphere that he was dancing very close to the fundamental theory of the Calculus. Something that wasn't rediscovered for 1600 years.

Rap

I seem to recall that there was some soul-searching about irrational numbers among the followers of Pythagoras and -- legend has it -- somebody actually was summarily pushed off a cliff for having discovered this abnormal and abominable anomaly. According to this story, for a long time it was a closely guarded secret until some other wise soul re-discovered it independently. So much of numbers was mixed up with religion and theology that the existence of irrational numbers seemed like nothing less than heresy.

Octal? That looks like decimal to me.

Euclid's Elements goes through the proof--it is groundbreaking as it was the first proof by contradiction (assume a proposition is true and show it leads to a contradiction). In the case of irrational numbers, you assume it is rational and can be expressed as a ratio of integers and then show that this is impossible.

A breathtaking method when you consider it was the first use of this logic--that lead to some rather spirited debates in its own right.

Rap

Sorry George, you're right its decimal.

Rap

Thanks for all your responses to this question. It's very interesting. Much more interesting than when we had to learn it. It was actually a question in a That's Life Magazine. They are great for an outlay of $3 australian, prizes go from cars to holidays and whatever and the puzzles overall aren't that hard. Some are tricky but that's OK.
WendyLou