Kendoku Rules: How the 6x6 Grid Differs From KenKen and Sudoku

The Core Rules of a 6x6 Kendoku Puzzle

A standard Kendoku puzzle uses a 6x6 grid, subdivided into six bold-lined regions or 'boxes', each measuring 3 cells by 2 cells. Your goal is to fill the grid with the digits 1 through 6, following three strict rules. First, each row must contain the digits 1-6 exactly once, just like in a standard 6x6 Sudoku Solving Guide. Second, each column must also contain the digits 1-6 exactly once. Third, each 3x2 box must contain the digits 1-6 exactly once.

The arithmetic component comes from the lightly shaded 'cages' that overlay the grid. Each cage has a target number and an operation (+, -, ×, ÷) in its top-left corner. The digits you place inside a single cage must combine, using the given operation, to produce that target. Digits may repeat within a cage, but only if the other rules (row, column, box) are not violated. For example, a cage marked '6+' means the sum of all digits in that cage must equal 6.

• Remember the three constraints: Row, Column, and 3x2 Box.
• Cage math is a guide, not a separate rule. The Latin square rules are always primary.

Kendoku vs. KenKen: A Detailed Comparison

While both puzzles use arithmetic cages, the foundational grid structure is their most significant difference. Kendoku enforces a 6x6 Latin square with additional 3x2 box regions. KenKen, on the other hand, uses a pure Latin square grid (also 1-6 in each row and column) with no internal box divisions. You can learn more about the pure form in our guide to KenKen Rules.

This structural difference changes the solving logic. In Kendoku, you can use classic Sudoku techniques like box-line reduction, because the boxes are fixed. In KenKen, elimination logic comes solely from row/column constraints and cage combinations. Another key difference is naming and availability; 'KenKen' is a registered trademark, leading to the generic name 'Kendoku' for similar puzzles found in many newspapers and puzzle books.

Kendoku vs. Sudoku: Logic and Difficulty

Kendoku and Sudoku share the same core Latin square objective. The major difference is the source of clues. In Sudoku, you are given many starting digits (givens). In Kendoku, you are given almost no starting digits. Instead, you receive arithmetic cages that define relationships between cells.

This makes the initial phase of a Kendoku puzzle feel more like a pure logic or math puzzle. You must deduce possible number combinations for cages, then cross-reference those with the row, column, and box constraints to place your first digits. The solving path often involves more calculation than Sudoku, but the elimination techniques from Sudoku vs KenKen comparisons, like hidden singles, become powerful once a few digits are placed.

• Start with the smallest cages (e.g., '2÷' or '3×') or the largest cages (e.g., '11+' in a 6x6), as they have the fewest possible number combinations.

Common Solving Strategies for 6x6 Kendoku

Effective Kendoku solving starts with cage analysis. Write down all possible digit combinations for each cage that satisfy the target and operation. For a '3-' cage with two cells, the only possibilities in a 1-6 puzzle are (4,1), (5,2), or (6,3). Immediately eliminate combinations that would force a duplicate digit into a single row, column, or box.

Next, look for crossover points. A cell belongs to a cage, a row, a column, and a box simultaneously. If a cage combination requires, for example, a 5 in a certain cell, check if that 5 is already used in that cell's row, column, or box. This interlocking constraint is where the puzzle solves itself. The logic is similar to the cross-referencing used in puzzles like Kakuro Rules, but with the added layer of the 3x2 box.

Which Puzzle Should You Play?

Choose Kendoku if you enjoy Sudoku's spatial logic but want a fresh challenge that starts from mathematical clues rather than givens. Its fixed boxes provide a familiar Sudoku feel within a more deductive framework. Choose KenKen if you prefer the purity of a Latin square challenge focused entirely on cage arithmetic without the extra box constraint. For a comparison of these styles, see our analysis of Sudoku vs KenKen.

Classic Sudoku remains the best choice for players who love pure deduction from givens and a wide range of advanced pattern-recognition techniques. Kendoku offers a compelling hybrid that strengthens mental arithmetic and logical deduction in equal measure.