I want to calculate the age of a person in May 22 of 2010. How do I go about doing that without having two visible date fields.

I looked at http://help.creator.zoho.com/Date-Calculations-and-Formula.html#3._How_can_I_calculate_the_age_of_a_person_from_a_given_Date_of_Birth? and other questions on that page and was unable to arrive at a solution.