The Roman numerals
Roman numerals have persisted over a millennium. But how was that possible? With these numbers it was very difficult, and in some cases, impossible to make calculations. Except for simple additions and subtractions, other calculations could only be made with great difficulty.
It should not be forgotten that Indian-Arab numbers only took hold in Europe in the 15th century. Unfortunately, thanks to the bloody Crusades.
But at this point the question must be asked: How could - the Roman architects - have built those majestic buildings? After all, a real calculation was impossible with certain numbers.
Except for the "V", in the sequence of numbers of a Roman numeral the letters are repeated up to three times. If the letter is lower than the next letter that follows, then its value is subtracted from the upper letter that follows it. If, on the other hand, a group of letters follow a letter of a higher level, then they are added to the previous letter which was higher. A dash above a letter multiplies by a thousand the nominal value of the letter.
One time you subtract and another time you add, but sometimes you leave it alone. Even if there is logic in this sequence of numbers, the illogicality of this logic prevents a decent calculation.
Imagine where to do some calculations with a differential. Or a simple vector calculation. So it was more than logical to have had to change the system.