Classic Sudoku · 43
Classic Sudoku · 43: a 9×9 Sudoku with 36 clues and one solution. Play online, use pencil notes and hints, or compare the complete answer.
Use rows and columns: R1C1 is row 1, column 1. Enter digits inside the squares.
Read the position, one decision at a time
Follow the deductions in order. Each step uses the grid after the preceding entry.
Reveal step-by-step explanations
Deduction 1: R1C8 = 3
This cell has candidates 3, 6, 7, 9, but 3 occurs in only this cell of row 1. This is a hidden single, not a guess between its candidates.
Check the existing digits: row 1: 1, 2, 5; column 8: 4, 5, 8; box: 1, 2, 4, 5. Each digit already present rules out that candidate in this cell.
Deduction 2: R2C5 = 5
This cell has candidates 5, 6, 7, 8, 9, but 5 occurs in only this cell of row 2. This is a hidden single, not a guess between its candidates.
Check the existing digits: row 2: 1, 2, 3, 4; column 5: 1, 3; box: 1, 2, 3. Each digit already present rules out that candidate in this cell.
Deduction 3: R8C8 = 1
This cell has candidates 1, 2, 6, 7, 9, but 1 occurs in only this cell of row 8. This is a hidden single, not a guess between its candidates.
Check the existing digits: row 8: 3, 5; column 8: 3, 4, 5, 8; box: 3, 4, 5, 8. Each digit already present rules out that candidate in this cell.
Deduction 4: R5C9 = 1
This cell has candidates 1, 2, 9, but 1 occurs in only this cell of row 5. This is a hidden single, not a guess between its candidates.
Check the existing digits: row 5: 4, 5, 7; column 9: 3, 4, 5, 6; box: 4, 5, 6, 8. Each digit already present rules out that candidate in this cell.
Understand this position
9×9 grid · 3×3 boxes · 36 clues · 45 empty cells
Start by inspecting row 1, column 2. From the starting grid, its legal candidates are 6, 8. Check the filled digits in that row, column and box before entering a number. Several candidates remain; this cell is not yet a naked single. Leave notes and compare another row or box.
Read the complete answer by row
5 · 6 · 7 · 2 · 9 · 4 · 1 · 3 · 88 · 1 · 3 · 6 · 5 · 7 · 2 · 4 · 99 · 2 · 4 · 1 · 8 · 3 · 6 · 7 · 52 · 7 · 5 · 4 · 1 · 9 · 3 · 8 · 66 · 3 · 8 · 7 · 2 · 5 · 4 · 9 · 11 · 4 · 9 · 3 · 6 · 8 · 7 · 5 · 24 · 5 · 2 · 9 · 3 · 1 · 8 · 6 · 77 · 8 · 6 · 5 · 4 · 2 · 9 · 1 · 33 · 9 · 1 · 8 · 7 · 6 · 5 · 2 · 4