Kakuro (also called cross-sum) is a number puzzle that looks like a crossword but is solved with arithmetic. Instead of words, you fill the white cells with digits 1 to 9 so that every horizontal and vertical run adds up to the number shown in its clue — and no digit repeats within a run.
Kakuro trains mental arithmetic and logical deduction at the same time. Because every clue is a sum, you constantly combine small addition facts with elimination — a perfect daily exercise for focus and number sense.
Kakuro sits naturally in our number-puzzle family. If you enjoy Sudoku, you'll recognise the elimination logic. If you like the clean binary logic of Takuzu, Kakuro adds a sum-based twist. And like Tectonic, it's all about placing digits without repeats — but with the extra layer of addition.
Kakuro is a cross-sum number puzzle. You fill the white cells with digits 1 to 9 so that every horizontal and vertical run adds up to the number shown in its clue, without repeating a digit within a run.
Sudoku uses 3x3 boxes and every row and column must contain 1 to 9 exactly once. Kakuro has no boxes: instead each run of white cells must add up to a given clue, and no digit repeats within a run.
Takuzu is a binary puzzle with only 0s and 1s, an equal amount per row and column. Kakuro uses digits 1 to 9 and the goal is a sum, not a balance of two values.
No. The rules are simple: each run adds up to its clue and no digit repeats in a run. The challenge comes from combining clues, which makes it a great daily brain workout.