Kakuro
Explore Game Details
Kakuro Rules & Strategies
Kakuro (also known as Cross Sums) is a logic puzzle. Fill each empty cell with a digit from 1 to 9 so that every horizontal and vertical run of consecutive white cells sums to the clue number at its start, with no digit repeated within a run.
Basic Rules
- Fill each white cell with a digit from 1 to 9
- Each horizontal run sums to the clue shown in the black cell to its left
- Each vertical run sums to the clue shown in the black cell above it
- No digit may repeat within any single run
- Every puzzle has exactly one solution found through logic
How to Play
- Select a difficulty level that matches your skill
- Read the clue sums: top-right is the run to the right, bottom-left is the run below
- Click an empty white cell to select it
- Enter a digit with the number buttons or keyboard (1-9)
- Use Check to verify your progress and highlight any mistakes
- Use hints if you get stuck, or Solve to see the full solution
Reading the Clues
- Black cells show sums for the runs they start
- The number in the top-right corner is the sum of the horizontal run to the right
- The number in the bottom-left corner is the sum of the vertical run below
- A black cell may contain one or both clues depending on its position
Quick Reference
- Start with the shortest runs - they have the fewest combinations
- Use pencil marks to track possible digits in each cell
- A two-cell run summing to 3 must be 1 and 2; summing to 4 must be 1 and 3
- Look for cells where only one digit fits after crossing out used digits
Solving Strategies
Beginner Strategies
- Unique sums: short runs often have only one possible combination
- Cross elimination: placing a digit removes it from the crossing run
- Single candidate: when only one digit fits in a cell, fill it in
- Start from clue-rich corners and work inward
Advanced Strategies
- Memorize two-cell magic sums: 3, 4, 16, 17 have unique combinations
- Use range analysis: a run's sum limits the digits that can appear
- Combine constraints from crossing runs to eliminate candidates
- Look for interlocking runs where a digit's placement is forced
Pro Tips
- Don't guess! Kakuro is solved through logic, not trial and error
- Update candidate marks immediately after placing each digit
- Take breaks if you're stuck - fresh eyes often spot solutions
- Practice regularly to recognize common combinations faster
- Start with easier puzzles and gradually increase the difficulty
Frequently Asked Questions
Have another question? Let us know.
What is the goal of Kakuro?
The goal of Kakuro (also called Cross Sums) is to fill the blank cells with digits from 1 to 9 so that the digits in each horizontal or vertical run add up to the clue number at the start of that run, and no digit is repeated within a run. It is a logic puzzle that sharpens your reasoning and arithmetic skills.
How should I start playing Kakuro?
Choose a difficulty level that suits you (easy, medium, hard, or expert) and study the clue numbers in the black cells. Each black cell shows the sum for the run to its right (top-right corner) and the sum for the run below it (bottom-left corner). Start with short runs, because short runs have fewer possible combinations. For example, a two-cell run summing to 3 must contain 1 and 2. As you place digits, cross out the used numbers in the crossing runs and keep narrowing down the possibilities until the whole grid is filled.
How can I improve my Kakuro skills?
Regular Kakuro practice improves logical reasoning, mental arithmetic, and patience. To improve, memorize the possible combinations for short runs, such as sums of 3, 4, 16, and 17 for two-cell runs, which each have only one combination. Use pencil marks to track candidate digits in each cell. When you place a digit, immediately update the candidates of the crossing runs. Start with easier puzzles and gradually move to harder ones. If you feel stuck or frustrated, take a short break and return with fresh eyes.
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