How did the ancient Romans add up their numbers?
by 
singwell-is off researching a lot
ANSWERS: 2
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Remove subtractive notation (if applicable; this was not common in Roman times). Concatenate terms. Sequence numerals high to low. Simplify result by summation of internal numerals. Apply subtractive notation, if desired. Multiplication and division were a nightmare; addition and subtraction relatively simple. All the same, you can easily see how the Arabic system caught on so quickly! http://en.wikipedia.org/wiki/Roman_arithmetic
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DavidHume is exactly right (if a bit abbreviated). First note: The Romans didn't use the "subtractive notation". We say IV means four. They said IV and VI are the same: six. The idea of IV for four was invented 1700 years later. So to add six (VI) and six (VI) the answer is VIVI again, they didn't care that the letters are all jumbled up. To simpify the answer, make a tally: so every five I's become a V. Every two V's become an X etc. Multiplication was easier than it is today. Instead of learning each of your ten times table, you only needed your V, X, L, and C times table: The easy ones: X*X=C, X*C=M, V*X=L, V*C=D, L*X=D, The hard ones: V*V= XXV, V*L=CCL, L*L=MMD That's it. Now just multiply the first number by each letter of the second. e.g. 22*36 XXII * XXXVI do XXII by X (three times) CCXX CCXX CCXX do XXII by V LLVV do XXII by I XXII answer is CCXXCCXXCCXXLLVVXXII (which could be simplified by tally as you go along if necessary: six C's and two L's = DCC eight X's and two Vs = LXXXX) answer = DCLXXXXII = 692
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