🧠 Expert · 26 given numbers · ID expert-21
Expert Sudoku No. 21
A expert puzzle with exactly one solution. Techniques needed: naked single, hidden single, pointing pair, box/line reduction, naked pair, forcing chain.
The sheet below is exactly what prints on one A4 or Letter page. Choose “Save as PDF” in the print dialog if you prefer a file.
Keyboard: arrow keys to move, 1–9 to fill, Backspace to erase, N to switch notes.
Solution (hidden until you want it)
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About this puzzle
Expert puzzles need at least one top-tier technique: naked or hidden quads, Swordfish or a forcing chain (testing a two-candidate cell and following the consequences). Looking for a different challenge? Easy, Medium or Hard puzzles are on the printable Sudoku page.
Need a break from the numbers?
Try a hard riddle
Sudoku and riddles train the same muscle: spotting what must be true. Here are a few hard riddles with answers.