Up to February 28 in the calendar you are converting from add one day less or subtract one day more than the calculated value. Remember to give February the appropriate number of days for the calendar you are converting into. When you are subtracting days to move from Julian to Gregorian be careful, when calculating the Gregorian equivalent of February 29 (Julian), to remember that February 29 is discounted. Thus if the calculated value is -4 the Gregorian equivalent of this date is February 24.
How many days you add to convert days from a calendar? (If the question is unanswerable, say "unanswerable")
unanswerable