An eight-inch checkerboard can be covered with 32 one-by- two-inch dominos in thousands of different ways. If two opposite corners of the board are removed, 31 dominoes should be sufficient to cover the remainder. But the first attempt to do so ends in failure. So does the second. Everything proceeds smoothly most of the time; minor difficulties arise, but they are met successfully until the end. Then the would-be coverer finds himself with one domino in hand and two non-adjacent squares staring up at him from the board.