How Do I Know Which Sudoku Technique to Use Next?

Step #1: Review What Changed After Your Last Move

You know several Sudoku techniques, but you’re stuck deciding which one to try. Should you scan again, study your pencil marks, or search for a more advanced pattern?

Start with what the puzzle is showing you. You don’t need to force a particular technique into every puzzle.

After placing a number, check the cells sharing its row, column, and box. Update the pencil marks affected by that placement, using the method you’re learning.

Did anything become clearer? A cell might now have only one possibility. Or a number might have only one possible location in a row, column, or box.

Follow that new information before moving to another part of the board.

Step #2: Check Familiar Methods Before Moving On

A difficult puzzle can still contain a simple move. Getting stuck doesn’t automatically mean it’s time for your most advanced technique.

Work through your familiar checks deliberately:

• Review the numbers you’re currently scanning.
• Look at rows and columns as well as boxes.
• Check areas with only a few empty cells.
• Review the effects of recent placements and eliminations.

The goal is to find useful information, even when you can’t place another number immediately. That information may help reveal a pattern later.

In how to start a hard Sudoku puzzle, I explain how basic solving methods help build the information needed for more advanced techniques.

Step #3: Let the Pattern Guide Your Choice

Once your familiar checks stop producing progress, look for the starting patterns of techniques you’ve learned.

Instead of asking, “Which technique should I force myself to try?” ask, “What do I see that matches something I know?”

For example, some techniques depend on identifying cells with exactly two possibilities. Others require a particular arrangement of a number across the grid.

Those clues give you a reason to investigate a technique. They don’t prove it applies yet.

If the required pattern isn’t there, move on. Knowing a technique doesn’t mean every puzzle will give you an opportunity to use it.

My article on what to do when the One-Thru-Nines doesn’t work discusses this connection between the information on the board and the methods you try next.

Step #4: Check the Whole Pattern Before Using It

Recognizing part of a pattern can be exciting, especially after you’ve been stuck for a while. Take a moment to verify it before eliminating a possibility.

Ask yourself:

• Have I identified every cell the technique requires?
• Do the required relationships between those cells hold?
• Am I interpreting my pencil marks correctly?
• Can I explain why this elimination follows?

If you can’t explain the move, revisit the lesson or a worked example. A familiar-looking arrangement is a starting point for checking your reasoning.

And if you’re tempted to choose between two numbers just to get moving, pause. In picking the right number to solve your Sudoku, I explain why learning the logical next move is more useful than making a guess.

Step #5: Return to the Basics After Making Progress

An advanced technique may eliminate a possibility without placing a number. That elimination can still change what’s available elsewhere.

Review the affected cells and their rows, columns, and boxes. Check whether the new information reveals a simpler move.

You don’t have to stay with advanced techniques for the rest of the puzzle. Move between your methods as the information changes.

If you repeatedly reach a point where you don’t recognize any useful patterns, make that your next learning goal. Explore the Sudoku Professor courses for instruction and practice resources covering different solving skills.

The next technique to use is the one whose conditions you can identify and verify. Start with familiar checks, follow the clues on the board, and make each move for a reason.