In Sudoku, how many smaller sub-grids are in one puzzle?

9

Who played the love interest in Taylor Swift’s music video "You Belong With Me"? In track and field, how many laps around a standard athletics track is a 1500-meter race? In what year did MTV first broadcast? Who became Emperor of Japan in 1989, beginning the Heisei era? What international assembly did the U.S. Senate block entry into after World War I?