In box 8, the digits 1, 6 and 7 can go only in the 3 highlighted cells. Those cells are reserved for these digits, so remove all other candidates from them.
What to look for
Choose three digits and find all their candidate positions in one row, column or box. Together, those positions must cover exactly three cells. Each digit can appear in two or three of those cells.
Why it works
All three digits must fit into those three cells. Using another digit in any of the cells would leave too little room for the triple.
Try it step by step
- Choose three digits and find all their candidate positions in one house.
- Check that those positions cover exactly three cells.
- Remove every other candidate from the three cells.
Try it on a real puzzle
Start with the highlighted step, then keep solving. Use "Apply hint" to make the suggested change, or enter your own digits and candidate notes. Use "Undo" to reverse your last change.
| C1 | C2 | C3 | C4 | C5 | C6 | C7 | C8 | C9 | |
|---|---|---|---|---|---|---|---|---|---|
| R1 | |||||||||
| R2 | |||||||||
| R3 | |||||||||
| R4 | |||||||||
| R5 | |||||||||
| R6 | |||||||||
| R7 | |||||||||
| R8 | |||||||||
| R9 |
Use the arrow keys to move, 1-9 to enter a digit and Backspace or Delete to clear a cell. To add or remove a candidate, press C and then 1-9.
Source puzzle number: 276324 · Play this puzzle from the start
A simple example
If 1, 2 and 3 are candidates only in the first three cells of row 1, those cells can keep only candidates 1, 2 and 3.
A house is a row, column or 3 × 3 box. A line is a row or column. Two cells "see" each other when they share a house. R1C3 means row 1, column 3. Boxes are numbered 1-9 from left to right and top to bottom. Braces such as {1, 2} show a cell's candidates, not confirmed digits.