Part of the 3M Bookshelf SeriesPlayers take turns placing their numbered tiles on the board so that their sum, both rank and file, is equal to a multiple of the 'multile' number that is selected for that round. Highest score once all the tiles have been placed wins.The red 'multiles' were introduced in the 1968 edition the previous (1964) edition didn't have those and played as if the '5' multile were always the one drawn. - BoardGameGeek