Kakuro puzzles are like a cross between a crossword and a Sudoku puzzle. The kakuro grid, unlike in sudoku, can be of any size. It has rows and columns, and dark cells like in a crossword. And, just like in a crossword, some of the dark cells will contain numbers. However, in a crossword the numbers reference clues. Clues are shown on the left and right sides of “across” words, and on the top and bottom sides of “down” words. In a kakuro, the numbers are all you get! They denote the total of the digits in the row or column referenced by the number. Some cells will contain two numbers. Instead of letters, each block contains the digits 1 through 9. Within each collection of cells - called a run - any of the numbers 1 to 9 may be used but, like sudoku, each number may only be used once. The same digit will never repeat within a word. If you add the digits in a word, the sum will be the number shown in the clue.