Sudoku looks like a cluttered Excel sheet to the average person. When asked where the Netherlands’ ‘sudoku rage’ came from at the beginning of this century, many would say Japan. And that's correct. The craze reached the Netherlands in 2004, but the puzzle came to Japan from the United States much earlier than that. Of the 81 boxes that must all be filled with a number from 1 to 9, at least 17 must be shown at the beginning to complete the puzzle. There’s no higher mathematics involved. The numbers in the magic square mean nothing.