Classic Sudoku · 27
Classic Sudoku · 27: 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: R1C3 = 8
After the preceding deductions, row 1, column 3 has only candidate 8. Its row, column and box exclude every other digit. Enter 8, then update the remaining candidates; this conclusion does not require consulting the completed answer.
Check the existing digits: row 1: 2, 4, 5, 6; column 3: 1, 3, 6, 7, 9; box: 2, 5, 9. Each digit already present rules out that candidate in this cell.
Deduction 2: R2C5 = 8
After the preceding deductions, row 2, column 5 has only candidate 8. Its row, column and box exclude every other digit. Enter 8, then update the remaining candidates; this conclusion does not require consulting the completed answer.
Check the existing digits: row 2: 2, 5, 6, 9; column 5: 1, 2, 3, 4, 5, 7; box: 2, 4, 5, 6. Each digit already present rules out that candidate in this cell.
Deduction 3: R3C3 = 4
After the preceding deductions, row 3, column 3 has only candidate 4. Its row, column and box exclude every other digit. Enter 4, then update the remaining candidates; this conclusion does not require consulting the completed answer.
Check the existing digits: row 3: 5, 7; column 3: 1, 3, 6, 7, 8, 9; box: 2, 5, 8, 9. Each digit already present rules out that candidate in this cell.
Deduction 4: R3C4 = 3
After the preceding deductions, row 3, column 4 has only candidate 3. Its row, column and box exclude every other digit. Enter 3, then update the remaining candidates; this conclusion does not require consulting the completed answer.
Check the existing digits: row 3: 4, 5, 7; column 4: 1, 4, 5, 9; box: 2, 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 3. From the starting grid, its legal candidates are 8. Check the filled digits in that row, column and box before entering a number. Only one candidate remains: this is a naked single.
Read the complete answer by row
7 · 2 · 8 · 5 · 4 · 6 · 3 · 9 · 13 · 1 · 9 · 7 · 8 · 2 · 5 · 4 · 65 · 6 · 4 · 3 · 9 · 1 · 7 · 8 · 22 · 4 · 5 · 6 · 3 · 9 · 1 · 7 · 81 · 8 · 7 · 2 · 5 · 4 · 6 · 3 · 96 · 9 · 3 · 1 · 7 · 8 · 2 · 5 · 48 · 5 · 2 · 4 · 6 · 3 · 9 · 1 · 79 · 7 · 1 · 8 · 2 · 5 · 4 · 6 · 34 · 3 · 6 · 9 · 1 · 7 · 8 · 2 · 5