Kakuro is like a crossword puzzle with numbers. Each "word" must add up to the number provided in the clue above it or to the left. Words can only use the numbers 1 through 9, and a given number can only be used once in a word. Every kakuro puzzle has one and only solution, and can be solved through logic alone.

Kakuro Hint: Start with clues that only have one valid combination. For example, 3 in 2 must be 1 and 2, and 23 in 3 must be 6, 8, and 9.