Snyder Notation for Beginners
One Simple Rule That Makes Sudoku Easier
Heard about Snyder Notation but not sure what it is? You're in the right place. This guide explains the technique in the simplest possible terms — no jargon, no complicated examples. By the end, you'll understand the one rule that makes Sudoku significantly easier.
- What it is: A way to write small helper numbers in Sudoku cells
- The rule: Only write a number when it can go in exactly 2 cells in a box
- Why it helps: Keeps your grid clean and makes patterns obvious
- Time to learn: About 5 minutes
What is Snyder Notation?
Snyder Notation is a way of writing small "helper numbers" (called candidates or pencil marks) in Sudoku cells to help you solve puzzles.
It was developed by Thomas Snyder, who won the World Sudoku Championship four times. He created this method to solve puzzles faster — and it works for beginners too.
When solving Sudoku, you often think "this cell could be a 3 or a 7" — but then you forget. Snyder Notation gives you a simple system for writing these notes so you don't lose track.
The key difference from other notation methods? You write less. Much less. This keeps your grid clean and makes it easier to spot patterns.
The One Rule
Snyder Notation has just one rule:
Write a small number in a cell only when that number can go in exactly two cells within the same 3×3 box.
That's it. If a number could go in three cells? Don't write anything. Four cells? Don't write anything. Only when it's narrowed down to exactly two possibilities do you make a mark.
Why "Exactly Two"?
This might seem arbitrary, but there's a good reason:
The Magic of Two
- Two = Actionable. When you later figure out one of those cellscan't have that number, you immediately know it goes in the other cell.
- Two = Clean. If you wrote numbers every time they had 3, 4, or 5 possibilities, your grid would be covered in tiny numbers and impossible to read.
- Two = Patterns. When you see the same number marked in two cells that share a row, that's a useful pattern called a "pointing pair."
How to Do It
Pick a 3×3 box to examine
Choose a number (1-9) to check
Count the possibilities
If exactly two cells remain, mark them
Repeat for other numbers and boxes
Simple Example
Let's walk through a real example:
Scenario
Imagine a 3×3 box where we want to find where 5 can go:
- • Cell A: Already has a 3 → Can't be 5
- • Cell B: Empty, but same row already has 5 → Can't be 5
- • Cell C: Empty, no conflicts → Could be 5 ✓
- • Cell D: Already has a 9 → Can't be 5
- • Cell E: Empty, no conflicts → Could be 5 ✓
- • Cells F-I: Various conflicts → Can't be 5
Later, if you discover Cell C must be something else (say, a 7), you'll immediately know Cell E must be the 5. That's the power of Snyder Notation.
Common Mistakes to Avoid
Some beginners write a number whenever it has 2, 3, or 4 possibilities. This defeats the purpose — your grid becomes cluttered and hard to read. Only write when it's exactly two.
When you place a number, it might reduce a 3-possibility situation to 2. Go back and add Snyder marks when this happens.
Snyder Notation specifically looks at 3×3 boxes. While you consider row/column constraints when counting, the "exactly two" rule applies within each box.
When to Use Snyder Notation
Snyder Notation is perfect for:
✅ Great For
- • Easy and medium puzzles
- • When you're learning Sudoku
- • Speed solving
- • Keeping your grid readable
- • The first phase of any puzzle
⚠️ You'll Need More For
- • Expert-level puzzles
- • Advanced techniques (X-Wing, etc.)
- • When Snyder marks aren't helping anymore
(You can switch to full notation for these — see ourcomparison guide)
Next Steps
Now that you understand the basics, here's how to improve:
Try It Now
Practice Snyder Notation on our free puzzles. Use corner marks for your Snyder notes.
Play Free Sudoku