How did the Romans actually do any mathematical calculations with Roman numerals? Without the concept of places (units, tens, etc.) how did they add, subtract, multiply, divide, sell slaves, and build aqueducts?
They did establish arithmetical techniques, and I have seen references or instructions to some of the basics, but they don't appear to have developed mathematics to any great depth so the awkwardness of their numerals was not a great problem to them. Perhaps their maths didn't advance because they could not conceive a more malleable number-system!