pencilmark

A pencilmark is a method used primarily in puzzle-solving, especially in Sudoku, Kakuro, and similar logic puzzles, to help players keep track of potential candidates or annotations within individual cells. Pencilmarks are small, often faint numbers, symbols, or notes written in the margins or within the puzzle grid using a pencil. They serve as a visual aid for players to note possible values that a particular cell might contain, based on the current state of the puzzle.

In Sudoku, for example, players commonly jot down candidate numbers in each empty cell to indicate which digits could still potentially fit there without violating the puzzle’s rules. As the solver progresses and more deducible information is obtained, these pencilmarks are refined or eliminated, facilitating logical deductions and reductions of possible options.

Pencilmarks are valued for their flexibility and readability. Since they are typically added and erased with a pencil, they allow for trial and error and iterative refinement during the solving process. They are especially useful for more challenging puzzles requiring complex deduction, enabling solvers to keep track of multiple possibilities concurrently.

The use of pencilmarks can vary depending on the puzzle type and the solver’s personal preference. Some advanced solvers may rely heavily on pencilmarks, while others prefer minimal markings, opting for a more done-in-one approach. Overall, pencilmarks remain a fundamental tool in puzzle solving, supporting logical reasoning and efficient problem-solving strategies.