Roman numerals were born from the carving of successive notches that were engraved on wood or other materials. It is believed that in reality, they were not signs to do operations with but simple abbreviations to express and remember numbers. The carving up to number 4 was simple and in order not to make reading difficult, another sign was needed. So the Romans changed the appearance of the notch of the multiples of 5,10 as for example IIIIVIIIIXIIIIVIIIIX.
Roman Numerals were made of a combination of seven letters. The smaller number was added only if placed after the bigger number and subtracted when placed before. We can easily say that the number represented in the end is given by the difference or the sum of the values of each symbol that composes it.
Roman numerals were the primary tool used for counting until the establishment of the Arabic system introduced in the European continents during the 11th century. But despite all this, they are still used for cornerstones, chapter tiles, church leaders and more all around the world. Without forgetting the use of the roman numerals for astrology, theology, seismology, photography and also pharmaceuticals.