This puzzle is similar to a crossword puzzle. The gray blocks with white "clue" sums in the top-right corner represent the "across" lanes. Those with "clue" sums in the bottom-left corner represent "down" lanes. Each lane is made up of at least two white blocks, in which you should put digits from 1 to 9. When added up, the number in each white box should equal the down or across "clue" sums. Make sure you don't repeat any digit in a single lane. The solution is below.