How did the Romans do division, multiplication etc.?

Question

How could they do division and multiplication with Roman Numerals?

Answer 1

It was quite easy, really.

For example, II x III = VI, and XV / V = III

See how easy it was!

Now, to be serious, the Romans didn't do arithmetic or algebra as you and I know it. They simply dealt with the MEANINGS of the numbers, without manipulating the integer symbols as we have learned to do. Simple calculations were just done in their heads and the answers written down, much as we would do it by knowing the multiplication tables up to 12 x 12 until the introduction of calculators ruined mental arithmetic.

(If you go to India today, you may marvel, as I did, at the agility in mental arithmetic that the lowliest store clerk exhibits. When I complimented someone on the rapidity with which she added up a complicated bill AND took off a discount of 16 %, ALL IN HER HEAD, she looked at me in and said "But it is only mental arithmetic!" That art has been largely lost in the West. Only at the final exit was her calculation checked by the one calculator in the store --- it was perfect!)

As far as the Romans were concerned calculations were done with tools like the abacus. The numerical symbols were only assigned to the INPUTS that they fed into the abacus, or the RESULTS that came out of it. Remember that they had no "zero" (" 0 ") which was another great hindrance to doing what we do with such relative ease today.

So, basically, they couldn't do a lot of the math that we can do today, but the abacus etc. could handle all the calculations required for trade.

Live long and prosper.

Answer 2

With great difficulty. Roman numerals are extremely clumsy for calculating. Even addition and subtraction are difficult, and the problems all stem from the fact that their place value system was very flawed. If I remember correctly, however, didn't the mathemeticians use the abacus? Just a wild guess.

Answer 3

http://mathforum.org/dr.math/faq/faq.roman.html#calc

for future reference, I just went to yahoo and typed:
"roman numerals" multiplication

and it was the very first hit.