The Romans did not follow the usual Greek practice in alternating 29- and 30-day months and a every other year. Instead, their 1st, 3rd, 5th, and 8thmonths had 31days each; all the other months had 29days except February, which had 28 days in common years, for a total of 355 days. The Roman intercalary month always had 27days, but was placed "within" the month of February alternating between after the Terminalia on the 23rd (""), and after the following day on the 24th; the remaining days of February were replaced by the corresponding days of Mercedonius (these last of February were actually named and counted inclusively in days before the calends of March and were traditionally part of the celebration for the new year). This seems to have arisen from Roman superstitions concerning the numbering and order of the months. The arrangement of the Roman calendar similarly seems to have arisen from Pythagorean superstitions concerning the luckiness of odd numbers.