What are the rules in changing Hindu-arabic into roman numeral?

Answer 1

Today's rules of converting Hindu-Arabic into Roman numerals are confusing to say the least.

Read any reference books regarding the history and evolution of mathematics and what they all have in common is that the Romans were not well inclined to mathematics because their numeral system was cumbersome and almost impossible to perform arithmetical operations.

But in fact the Romans were excellent mathematicians and their numeracy system was by far the most advanced in the known ancient world and an advantage it has over the numeracy system we use today is that it doesn't need a nought figure for place value purposes.

Today most people find it difficult to convert Hindu-Arabic numerals into Roman numerals. This is because the way we write out Roman numerals today is different to the way that the Romans did themselves because today's rules governing the Roman numeral system were introduced during the Middle Ages and that was centuries after the decline of the Roman Empire.

Take for instance the number 1999 today it is written out as MCMXCIX but the Romans themselves probably wrote it out as IMM and to multiply it by 10 would work out as X(XX) which is -10+20,000 =19,990

So where do you start when you try to multiply MCMXCIX by 10?