Why are numbers in Arabic (not Arabic numerals) written from left to right when the language is written from right to left?

Question

Or maybe the question should be why are (Western) Arabic numerals (i.e., 1, 2, 3…) written from left to right?

My question is why is 125 written ١٢٥ and not ٥٢١

In: 38

Answer 1

Arabic derives from earlier scripts also written right to left. The numbers were borrowed from India, where the scripts are left to right.