Pencil Marks and Snyder Notation
How to record candidates with pencil marks, and the disciplined Snyder method that keeps your grid uncluttered.
Pencil marks are the small candidate digits you write into an empty cell to remember which numbers can still go there. They turn the invisible bookkeeping of a solve into something you can see, which is essential once a puzzle moves past the easiest deductions.
There are two broad styles. Full pencil marks record every candidate in every cell; Snyder notation records far less, on purpose, to keep the grid readable. Knowing both — and when to switch — is one of the highest-value basic skills.
Full pencil marks
In the full method you write, in each empty cell, every digit that is still legal there. The grid fills with small numbers, but the payoff is that naked singles, naked pairs and many other patterns become visually obvious. Keep the marks small and in a consistent corner layout so a cell with one mark stands out.
- Write every legal digit in each empty cell.
- A cell showing one mark is a naked single — place it.
- When you place a digit, erase it from the peers' marks.
Snyder notation
Snyder notation, popularised by world champion Thomas Snyder, is a disciplined alternative that records far fewer marks. You go box by box and digit by digit, and you pencil a digit only when it has exactly two possible cells in that box. Digits with three or more options are left unmarked for now.
The result is a sparse grid in which hidden pairs and pointing patterns leap out almost immediately, because the only marks present are the high-signal ones. Many fast solvers start every puzzle in Snyder notation and only add full marks if they get stuck.
- Mark a digit in a box only when it has exactly two candidate cells there.
- Skip digits with three or more options until later.
- Two matching marks expose hidden pairs and pointing pairs at a glance.
Frequently asked questions
- What is Snyder notation?
- A pencil-marking discipline where you mark a digit in a box only when it has exactly two possible cells. It keeps the grid sparse so hidden pairs and pointing patterns are easy to spot.
- Should I use full marks or Snyder notation?
- Many solvers start in Snyder notation for speed and switch to full pencil marks only when a puzzle stalls and they need the extra detail to find an elimination.
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