Interactive Solving Lesson
Practice Snyder Notes and Pencil Marks
Learn Snyder notation by practicing pencil marks on an interactive Sudoku board. Place useful pencil marks without filling every empty cell with every possible candidate. Choose a digit and identify the boxes where that digit can occupy exactly two cells.
The Snyder Rule
Within a single 3×3 box, pencil in a digit only when that digit has exactly two possible cells in the box. Those two marks preserve a useful either-or relationship without covering the board in notes.
Snyder notation is box-based. A digit appearing in exactly two cells of a row or column is not, by itself, a Snyder pair.
Practice Position 1
Find the Snyder pairs for digit 1
Select every empty cell that belongs to a valid two-cell box pair.
Choose a digit:
Why Use Snyder Notation?
Full candidate notation records every possible digit in every empty cell. Snyder notation begins more selectively. It records the digits confined to exactly two cells within a box, making locked candidates, pairs, and later interactions easier to see while the grid remains readable.
For each selected digit, scan one box at a time. Eliminate cells that already see that digit in their row or column. If exactly two cells survive, mark both. If one cell survives, you have a placement. If three or more survive, leave that digit unmarked in that box for now.
When Should You Expand the Notes?
Snyder notation is most effective during the earlier and middle stages of a puzzle. When progress stops and advanced patterns require a fuller candidate picture, expand the notes deliberately. Snyder notation is a disciplined starting system—not a rule that forbids complete candidate notation later.
Snyder Notation Questions
Do the two cells need to share a row or column?
No. They only need to be the final two possible cells for that digit inside the same 3×3 box. Sharing a row or column may create an additional locked-candidate relationship, but it is not required.
Should I mark a digit with three possible cells in a box?
Not in basic Snyder notation. Wait until eliminations reduce that digit to exactly two possible cells, unless you intentionally decide to expand into fuller candidate notation.
Does a Snyder pair mean those cells are bivalue cells?
No. The pair describes two possible locations for one digit inside a box. Either cell may still contain several other candidates.
Use Snyder Notes in a Live Puzzle
SudokuParadise includes an optional Snyder Notes layer on its complete solving board. Generate a fresh puzzle, enter your own, or switch the assistance off and Fly Blind.
Play Sudoku with Snyder Notes