Calculating Age based on Document Date in months

Hi, I'm trying to write a formula that will calculate a patient's age based on the visit date and then converting it into months. Anyone know how to do that?
The variables would be:
{DOCUMENT.CLINICALDATE}
{PERSON.DATEOFBIRTH}The next will calculate age in years
({DOCUMENT.CLINICALDATE} - {PERSON.DATEOFBIRTH}) / 365

The next will calculate age in months
({DOCUMENT.CLINICALDATE} - {PERSON.DATEOFBIRTH}) / 365 * 12