Arabic numerals did not come into common use on coins until around the 1300s. In the transition period (approx.1250-1350), they also used an abjad system for shorthanding numerals using the letters of the Arabic alphabet (very similar to the modern Hebrew numeral system) - meaning the date is written as standalone letters, hidden in amongst the rest of the letters of the legend - much harder to find and decipher.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis