One aspect of the Commercial Revolution was that the barter system of trade was replaced by a system based on money and credit. Why were Arabic numerals needed to make this system work? Arabic numerals were easier for everyone to learn and use in transactions. Arabic numerals included the number 0, which does not appear in Roman numerals. Arabic numerals could be written in bank books without filling up the page. Arabic numerals allowed bankers to more easily calculate the interest on a loan.