How to Multiply Roman Numerals
Binary (halving and doubling) multiplication is one (but not the only) way people multiplied, not just in Rome but in many times and places. The oldest extant example is from the famous Rhind Mathematical Papyrus from three and a half millennia ago. <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Ancient_Egyptian_multiplication" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Ancient_Egyptian_multiplicatio...</a><p>Romans did not, in general, use Roman numerals directly for arithmetic. Roman numerals are a kind of serialization format for the state of a counting board. If you want to do arithmetic like a Roman, you need a bunch of lines on a paper (or the ground, or a board, or a piece of cloth) and a pile of tokens or pebbles. Deserialize your input numbers onto the counting board(s), perform your algorithm there, then serialize the result back into your record.