A Kakuro consists of a playing area of filled and empty cells similar to a crossword puzzle. Some black cells contain a diagonal slash from top left to bottom right with numbers in them, called “the clues”. A number in the top right corner relates to an “across” clue and one in the bottom left a “down” clue. The object of a Kakuro is to insert digits from one to nine into the white cells to total the clue associated with it. However no digit can be duplicated in an entry.