# of days left in Month

I am trying to create a formula field to show the # of days left in the month. The formula is referencing a Date field to go off of. Does anyone know why I am getting #Error!? If anyone knows how to fix this, do you also know a way to show the # of Business Days left in the month?

DAY(DATE(YEAR( Date__c ),MONTH( Date__c )+1,0))-DAY( Date__c )