Al Wolters gave a very thorough and sophisticated explanation of the term peres in the writing on the wall in Daniel 5.  I can’t reproduce it all, but one of the cool things that emerged from it was that the weights mentioned add up to 181, and the date of the Persian conquest of Babylon was the 181st day of the year, right after the rising of Libra (the “scales”) and right after the beginning of the civil year.  So, it’s the end of the year for Babylon and the beginning of a new year for Persia.