My sister is a smart cookie. She devised an Excel worksheet that calculates the ages of family members on their birthdays with a formula. (Names have been changed to protect the innocent.) You too can have your very own birthday calculator. Simply enter the names of your own family and their birthdates in the appropriate places, and save the file to your computer. This also works for anniversary dates. Remember to change the year in January and you can amaze everyone with your knowledge.