Kakuro (also known as "Cross Sums" or "Kakro") is a logic puzzle, a mathematical equivalent of the crossword puzzle. The puzzle consists of a board with filled and empty cells, similar to a crossword puzzle. Some black cells contain a diagonal slash from upper left to lower right with numbers in them called "clues". A number in the upper right corner represents the sum of the associated horizontal cells, and one in the lower left corner represents the sum of the associated vertical cells.
The goal of a Kakuro is to enter the digits from 1 to 9 in the white boxes to correspond to the associated sums. However, no digit may appear twice in an entry. For example, for the total sum 8, you can put 1 and 7, 2 and 6, but not 4 and 4.