Sudoku Rules

Intermediate Sudoku Rules & Normal Solving Techniques

Once you have mastered the basics, Easy puzzles will no longer pose a challenge. Moving on to Medium and Normal level Sudoku requires stepping beyond simple visual scanning and diving into pencil notes. By identifying interacting pairs, triplets, and directional alignments, you can easily clear blocked notes and unlock stubborn deadlocks.

6 Essential Intermediate Techniques

Normal Sudoku strategies focus on candidate elimination. Instead of placing a final number immediately, these techniques help you rule out impossible digits from empty cells, setting up instant single placements across the board.

1. Naked Pairs

A Naked Pair occurs when two cells within the same unit (row, column, or 3×3 block) contain the exact same two candidates and no other digits. Because those two numbers are strictly locked into those two cells, you can safely eliminate both candidates from every other cell in that shared unit.

2. Hidden Pairs

A Hidden Pair happens when two specific candidates appear exclusively inside two cells of a unit, even if those cells hold other extra pencil notes. Since those two numbers have nowhere else to go in that unit, all other extra candidates can be stripped away from those two cells, turning them into a clean Naked Pair.

3. Naked Triple

A Naked Triple is formed when three cells in a single unit contain a total pool of no more than three candidates (e.g., [1, 2], [2, 3], and [1, 3]). Because these three digits are locked into these three spots, you can delete all three numbers from the pencil notes of every other cell in that row, column, or block.

4. Hidden Triple

A Hidden Triple occurs when three candidate digits appear only within the same three cells of a row, column, or block, hidden beneath other pencil notes. Because those three target numbers are forced into those three spots, you can erase every other non-triple candidate from inside those three cells.

5. Pointing Pairs & Triples (Pointing)

The Pointing technique relies on the intersection of a 3×3 block and a line (row or column). When a candidate inside a 3×3 block is restricted to a single row or column, that candidate must land in one of those block cells. As a result, you can eliminate that digit from the rest of that line outside the block.

6. Claiming Pairs & Triples (Claiming / Box-Line Reduction)

Claiming is the exact reverse of Pointing. When a candidate along a full row or column is restricted entirely inside a single 3×3 block, that line “claims” the number for that box. Consequently, you can safely delete that candidate from all other empty cells within that 3×3 block.

Ready to Bridge the Gap?

Mastering candidate reduction is the key to tackling intermediate Sudoku without getting stuck. Turn on your pencil notes, scan for locked sets and pointing lines, and watch hard puzzles become manageable!

Put your skills to the test: Try our Medium Sudoku Puzzles today to practice Naked Pairs, Triples, and Intersection Reductions in real time!