Start with the idea
Start with three cells in the same row, column, or 3x3 box. In this example, three cells in row 7 can only use 1, 4, and 7 between them. Those numbers are reserved for those cells, so other cells in the row cannot use them.
Look for this pattern
Look for a small group of squares in the same row, column, or box. The group can reserve a matching set of numbers.
This empty board keeps the puzzle numbers out of the way so the pattern is easier to see.
Example
5
3
7
6
9
5
9
6
8
6
3
8
3
1
7
2
6
1
4
6
1
4
8
1
7
4
7
9
2
4
7
5
8
Look here firstLook across row 7. Three cells contain only the numbers 1, 4, and 7 between them.
This technique reviews candidates instead of solving a square right away.
Those three numbers must fill those three cells, so remove 1, 4, and 7 from the other cells in the row.
- Find three cells in the same row, column, or 3x3 box.
- Their notes use only three numbers total.
- Remove those numbers from the other cells in that area.
1, 4, and 7 triple1, 4, and 7 notes to remove
When to look for it
Use it when three sparse note cells in a row, column, or box combine to exactly three possible digits.
How to use it
- Find three cells in one row, column, or box whose combined notes are exactly three digits.
- Confirm each of the three cells contains only digits from that set.
- Remove those digits from the remaining cells in the row, column, or box.
Common mistakes
- The cells do not all need to contain all three digits.
- If the combined set is four or more digits, it is not a naked triple.