For the same reasons that we need a numeracy system today which is based on the Hindu-Arabic numeral system that was a lot easier than the Roman numeral system that it replaced.
Arab merchants needed an easier and faster way to calculate prices, quantities of goods, etc. The Roman numerals were just too slow and difficult to calculate, especially with larger numbers.
usage of hindu-arabic-numeral-system is a lot easier than roman numeral-system
they created Hindu-Arabic numerals as they are easy to write
what is hindu arabic numeral system and roman numeral
what is roman numeral system
Hindu Arabic numerals are the ones we use. 39 is already in Hindu-Arabic numerals.
12629 is already in Hindu-Arabic numerals
The Roman numerals LXVII=67 in Hindu Arabic numerals.
The Roman numerals of XX are the equivalent of 20 in Hindu-Arabic numerals
The Roman numerals of CCX are the equivalent of 210 in Hindu-Arabic numerals.
The Roman numerals of DCCC are the equivalent of 800 in Hindu-Arabic numerals
In Hindu-Arabic numerals, DCLXII would be 662.
437 is already in Hindu-Arabic numerals
The Roman numerals of XXVIII are the equivalent of 28 in Hindu-Arabic numerals
dcccxiii in Roman numerals is equivalent to 813 in Hindu-Arabic numerals.
12629 is already written in Hindu-Arabic numerals.
12 629 It is already in Hindu-Arabic numerals.