Mini Sudoku (6x6 grid) is the perfect introduction to Sudoku puzzles, but mastering it requires understanding key techniques. Whether you're a beginner or looking to improve your speed, these essential strategies will transform your solving approach.
1. The Elimination Method
The elimination method is the cornerstone of all Sudoku solving. It's simple: for each empty cell, identify which numbers cannot go there based on the numbers already present in the same row, column, and 2x3 box.
💡 How to Apply:
- Look at an empty cell
- Check its row - which numbers are already used?
- Check its column - which numbers are already used?
- Check its 2x3 box - which numbers are already used?
- The remaining number(s) are your candidates
Example: If a cell's row contains 1, 3, and 5, its column contains 2 and 4, and its box contains 1, 2, and 3, then only 6 can go in that cell!
2. Scanning Technique
Scanning is a systematic approach where you focus on one number at a time across the entire grid. This technique is particularly effective for finding "naked singles" - cells where only one number can fit.
Cross-Hatching
Cross-hatching is a specific scanning method where you draw imaginary lines through rows and columns where a number already appears, helping you identify where that number must go in remaining boxes.
🎯 Step-by-Step:
- Pick a number (let's say 1)
- Find all instances of 1 in the grid
- For each 2x3 box missing a 1, use elimination to find where it must go
- Repeat for numbers 2-6
3. Pencil Marking (Candidate Notation)
For harder puzzles, keeping track of possible candidates for each cell becomes crucial. Pencil marking involves writing small numbers in cells to indicate which values are still possible.
Benefits:
- Reduces mental load by externalizing your thinking
- Helps spot patterns more easily
- Prevents forgetting which numbers you've eliminated
- Essential for advanced techniques
4. Naked Singles and Hidden Singles
Naked Singles
A naked single occurs when a cell has only one possible candidate. These are the easiest to spot and should always be filled in first.
Hidden Singles
A hidden single is when a number can only go in one cell within a row, column, or box, even though that cell might have other candidates. The single is "hidden" among other possibilities.
🔍 Finding Hidden Singles:
Focus on one region (row, column, or box) at a time and ask: "Where can number X go in this region?" If there's only one valid cell, you've found a hidden single!
5. Box/Line Reduction
This intermediate technique uses the interaction between boxes and lines (rows/columns). If all candidates for a number in a box are confined to a single row or column, you can eliminate that number from the rest of that row or column outside the box.
6. Pattern Recognition
With practice, you'll start recognizing common patterns that indicate where numbers must go. Some patterns to look for:
- Pairs: Two cells in the same region with the same two candidates
- Symmetry: Mini Sudoku puzzles often have visual symmetry that can guide solving
- Corner patterns: The corners of boxes often reveal crucial placements
- Forced chains: When filling one cell forces a cascade of other placements
7. Starting Strategy
How you begin a puzzle matters! Follow this proven starting sequence:
- Quick scan: Look for any naked singles (cells with only one possibility)
- Focus on constraints: Start with rows, columns, or boxes that already have the most numbers
- Work systematically: Go number by number (1-6) using scanning
- Switch techniques: If you get stuck, switch to a different technique
⚡ Pro Tip:
The more constrained a region (more numbers filled in), the easier it is to solve. Always work on the most constrained areas first!
Common Mistakes to Avoid
- Guessing: Never guess! Every move should be logical
- Forgetting boxes: Remember to check the 2x3 boxes, not just rows and columns
- Working too fast: Speed comes with practice; accuracy first!
- Not marking candidates: For medium/hard puzzles, pencil marks are essential
Practice Makes Perfect
These techniques become second nature with practice. Start with easy puzzles to build your foundation, then gradually increase difficulty. Track your solving times to see your improvement!