Corrected: This story has been updated to reflect Ralph Pantozzi’s full statement. Corrected: A previous version of this story misstated the location of Kent Place School. It is located in Summit, N.J ...

How many fifth-graders in the U.S. took the AP Calculus AB exam last year? Radu Rosu of Chapel Hill wanted to find the answer. He knew of one child who did - his 10-year-old son, Paul Rosu, who earned ...