The APR on a credit card is calculated by taking the average daily periodic rate and multiplying it by 365. Calculate the APR on a credit card by using numbers on a statement with lessons from a math teacher in this free video on math calculations for daily life. Expert: Jimmy Chang Bio: Jimmy Chang has been a math teacher at St. Pete College for nearly a decade. He has a master's degree in math, and his specialties include calculus, algebra, liberal arts, math and trigonometry. Filmmaker: Christopher Rokosz