def scalar(self):
        """days since baseline date: Jan 1, 1900"""
        (year, month, day) = self.toTuple()
        days = firstDayOfYear(year) + day - 1
        if self.isLeapYear():
            for m in range(month - 1):
                days = days + _daysInMonthLeapYear[m]
        else:
            for m in range(month - 1):
                days = days + _daysInMonthNormal[m]
        if year == 1582:
            if month > 10 or (month == 10 and day > 4):
                days = days - 10
        return days