Classic Sudoku · 37
Classic Sudoku · 37: 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: R4C3 = 5
After the preceding deductions, row 4, column 3 has only candidate 5. Its row, column and box exclude every other digit. Enter 5, then update the remaining candidates; this conclusion does not require consulting the completed answer.
Check the existing digits: row 4: 3, 4; column 3: 1, 2, 7, 9; box: 1, 2, 3, 4, 6, 7, 8. Each digit already present rules out that candidate in this cell.
Deduction 2: R2C3 = 3
After the preceding deductions, row 2, column 3 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 2: 1, 4, 6, 8; column 3: 1, 2, 5, 7, 9; box: 2, 7. Each digit already present rules out that candidate in this cell.
Deduction 3: R4C5 = 6
After the preceding deductions, row 4, column 5 has only candidate 6. Its row, column and box exclude every other digit. Enter 6, then update the remaining candidates; this conclusion does not require consulting the completed answer.
Check the existing digits: row 4: 3, 4, 5; column 5: 1, 2, 4, 5, 7, 9; box: 3, 4, 7, 8, 9. Each digit already present rules out that candidate in this cell.
Deduction 4: R4C6 = 2
After the preceding deductions, row 4, column 6 has only candidate 2. Its row, column and box exclude every other digit. Enter 2, then update the remaining candidates; this conclusion does not require consulting the completed answer.
Check the existing digits: row 4: 3, 4, 5, 6; column 6: 1, 3, 4, 5, 6, 7, 8; box: 3, 4, 6, 7, 8, 9. 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 4, column 3. From the starting grid, its legal candidates are 5. 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
1 · 4 · 2 · 8 · 7 · 6 · 3 · 9 · 55 · 9 · 3 · 2 · 1 · 4 · 8 · 6 · 77 · 6 · 8 · 3 · 5 · 9 · 2 · 4 · 14 · 3 · 5 · 1 · 6 · 2 · 7 · 8 · 99 · 8 · 7 · 5 · 4 · 3 · 1 · 2 · 66 · 2 · 1 · 7 · 9 · 8 · 5 · 3 · 48 · 1 · 6 · 9 · 3 · 7 · 4 · 5 · 23 · 7 · 9 · 4 · 2 · 5 · 6 · 1 · 82 · 5 · 4 · 6 · 8 · 1 · 9 · 7 · 3