Be a puzzle pro

MONDAY, SEPTEMBER 9 INTERNATIONAL SUDOKU DAY

We asked Jason Zuffranieri, who has represented the U.S. at 10 World Sudoku Championships, for his tips to complete the number-placement puzzle—fast. His advice? “Start where the most activity is: a row, column or box that has the largest number of given digits. The information needed to complete an empty row, column or box is significantly more than one that’s mostly filled.” Another winning strategy: Try scanning for numbers that appear often. Says Zuffranieri, “If the upper-left box has a 2 and the upper-right box has a 2, that restricts where a 2 can go in the upper-middle box.”