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Sudoku strategy guide

Hidden triples: count three digits into three cells

A hidden triple appears when three digits can occur only within the same three cells of one unit, even when those cells show many extra notes.

Key idea

The three confined digits must occupy those cells, so every candidate outside the triple can be removed from the three cells.

See the move, step by step

Find digits 2, 6, and 7 hidden across row 5.

Step 1 of 4

Count digit locations

Scan row 5 by digit and note which cells can still hold 2, 6, and 7.

Row being scanned

Step 2 of 4

Confirm the three-cell cage

Every 2, 6, and 7 in row 5 is confined to R5C1, R5C2, and R5C4.

Row 5Hidden triple: 2, 6, 7

Step 3 of 4

Remove unrelated notes

The extra 5 and 9 at R5C1 and 4 and 9 at R5C2 cannot remain.

Confined tripleExtra candidates to remove

Step 4 of 4

Reveal the subset

The three cells now contain only the triple digits, making the underlying restriction explicit.

Hidden tripleCleaned cells

Try it on today's puzzle

Search hidden triples by candidate frequency. Three digits must be absent from every other cell in the unit.

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