What Is Kakuro, and How Do You Play It

The rules

Kakuro is played on a grid that looks like a crossword. Each run of white cells, across or down, has a clue that is a target sum. You fill the run with digits 1 to 9 so they add up to that sum, and no digit repeats within a single run. That no-repeat rule is what turns arithmetic into logic.

The key trick

Some sums have only one possible set of digits. A run of two cells that must total 3 can only be 1 and 2. A run of two totalling 17 can only be 8 and 9. These forced combinations, called magic blocks, are where you start. Fill them first and they constrain everything they cross.

How to make progress

• Look for the shortest runs and the most extreme sums, since those have the fewest combinations.
• Where an across run and a down run cross, the shared cell must satisfy both, which often pins it down.
• Keep candidate notes for each cell, just like Sudoku, and cross off digits as runs fill.

Why fans love it

Kakuro blends the grid logic of Sudoku with a little mental arithmetic, so it feels familiar yet fresh. If you enjoy the deduction in Shapedoku, Kakuro is a natural puzzle to try next.