The reason for February is only 28 or 29 days
Each calendar month has between 30 and 31 days, but February is only 28 or 29 days if it is a leap year, due to the retention of the previous Roman calendar.October 1582 calendar with 10 days does not exist
Before 1582, Europeans and colonies used a calendar based on the Julian calendar given by Emperor Julius Caesar in 46 BC.