I'm wondering if there is an easier way to accomplish what I'm trying to do.   I have a date field, Date_signed__c, and a number field, Duration_in_months_c.  I am calculating a new date field that is basically Date_signed + Duration_in_months using the following formula:

DATE( YEAR( Date_Signed__c ) + ROUND(Duration_in_months__c / 12 ,0), MOD(MONTH( Date_Signed__c) + Duration_in_months__c,12) , DAY( Date_Signed__c) )

I noticed that if you just add a number to a date field it adds days, but I'm not sure of an easy way to add months.  Is there a simpler way that I am missing?

Thanks