The Hidden Pairs technique is an advanced Sudoku solving strategy that allows you to identify and eliminate unnecessary candidates. This technique is based on identifying two numbers that can only appear in two cells within a row, column, or block.

When to Use the Hidden Pairs Technique?

Use this technique when you notice that two candidate numbers appear exclusively in two cells within the same row, column, or block, and nowhere else in that unit.

How to Identify a Hidden Pair?

1. Examine each row, column, and block for candidate numbers.
2. Look for two numbers that only appear in two specific cells within that unit.
3. If you find this configuration, you have identified a Hidden Pair.

Practical Example

Imagine you are working with numbers 3 and 7. If you see that 3 and 7 appear only in cells (2,3) and (5,3) within column 3, you can apply the Hidden Pairs technique.

This means you can eliminate all other candidates from those two cells, as they must contain exclusively 3 and 7.

Benefits of Using Hidden Pairs

• Eliminates unnecessary candidates, facilitating puzzle solving.
• Helps unlock complicated situations where other techniques don’t work.
• Improves your ability to recognize patterns and think strategically.

Tips for Practicing Hidden Pairs

• Practice regularly to become familiar with pattern identification.
• Don’t get frustrated if you don’t see it at first; it becomes easier over time.
• Combine Hidden Pairs with other techniques to maximize their effectiveness.

Conclusion

The Hidden Pairs technique is a powerful tool in your Sudoku solving arsenal. With practice and patience, you can master this technique and solve even the most challenging Sudokus.