About

Kakuro is often called the mathematical cousin of crosswords. The grid looks similar — blank squares to fill, numbered clues — but instead of words, you're filling sequences of digits that must sum to the clue number. Every digit from 1 to 9 can appear in a run, but no digit can repeat within the same run.

The puzzle is a beautiful intersection of arithmetic and logic. Small runs severely limit your options (a sum of 3 in 2 cells must be 1+2), while larger runs in combination with crossing sequences create rich constraint networks. Solving Kakuro exercises both number sense and deductive reasoning simultaneously.

Kakuro scales beautifully in difficulty — a small easy puzzle can be solved in 5 minutes, while a large expert grid can occupy an hour. For a coffee break, picking an easy or medium puzzle delivers that satisfying logical resolution within your available time.

How to Play

• Numbers in shaded diagonal cells are the "clue" sums for their horizontal or vertical run.
• Fill each white cell with a digit from 1–9 so that the run sums to its clue.
• No digit may repeat within the same horizontal or vertical run.
• Where a horizontal and vertical run cross, the digit satisfies both runs simultaneously.
• Fill all white cells correctly to solve the puzzle.

Tips

• Start with runs where only one combination of digits is possible (e.g., sum of 3 in 2 cells = 1+2).
• Use crossing constraints: if you know which digits are in a vertical run, they restrict the horizontal.
• Elimination works well: if a digit can't go in any cell but one within a run, it goes there.

History

Kakuro originated in the United States in the 1950s under the name "Cross Sums," published by Dell Magazines. Japanese puzzle publisher Nikoli popularized and refined it under the name Kakuro (short for "kasan kurosu" — addition cross) in the 1980s. Like Sudoku, Kakuro gained Western mainstream popularity in the mid-2000s when British newspapers began publishing it as a companion to their Sudoku columns.