147
Techniques · Hard
Hidden Triple
When three digits can only go in the same three cells of a unit, those cells belong to them. Every other candidate in those cells goes.
How to spot it
List the places for each missing digit in a busy unit. Three digits whose places fall within the same three cells form the triple.
Example
2
179
13469
13
1346
8
5
134
159
14
159
13489
2
1348
7
13
6
8
3
6
5
17
147
2
9
14
4
9
2
13
6
5
13
8
7
157
17
1357
1378
4
1378
6
2
9
6
8
137
1237
9
1237
5
4
13
17
5
178
137
1378
9
4
6
2
3
6
4
127
5
127
9
17
8
179
2
1789
46
178
46
13
137
5
In column 4, 4, 6 and 9 can only go in r1c4, r2c4 and r9c4, so all other candidates can be removed from those cells (Hidden Triple).
the pattern cells that lose a candidate (crossed out)