[drnet_ua]

public function countDown(startDate:Date = null, endDate:Date = null, itemCountStart:Number = 1000):Number 
		{						
			if (startDate == null) {
						startDate = new Date(2010, 12, 1);
			} 
 
			if (endDate == null) {
						endDate = new Date(2010, 12, 31);
			}
 
			var totalRange:Number = endDate.date - startDate.date;
 
			var timePassed:Number = endDate.date - new Date().date;
 
			return uint((timePassed / totalRange) * itemCountStart);		
		}

в пределах одного месяца работает