Naked Triple

Level 6 · Orange Belt (Green Stripe)

Strategy:

Requires:

Learn after:

Overview

A Naked Triple consists of three cells in a house that together contain exactly three candidates. These three digits must go in these three cells, so they can be eliminated elsewhere in the house.

How It Works

Find three cells in a house where the union of their candidates contains exactly three digits.
Each cell must have a subset of these three candidates (2 or 3 of them).
Eliminate these three candidates from all other cells in the house.

Example

Starting position

Look for Naked Triple.

Sudoku grid showing the initial puzzle state for Look for Naked Triple.

1

Scan row 5 for a triple

Check columns 3, 6 and 8 in row 5.

Sudoku grid illustrating step 1: Scan row 5 for a triple — Check columns 3, 6 and 8 in row 5.

2

1 is blocked from r5c3 by the column

Digit 1 cannot go in r5c3 because r9c3 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 2: 1 is blocked from r5c3 by the column — Digit 1 cannot go in r5c3 because r9c3 is already in this column. Remove the entry or choose a different digit.

3

2 is blocked from r5c3 by the column

Digit 2 cannot go in r5c3 because r3c3 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 3: 2 is blocked from r5c3 by the column — Digit 2 cannot go in r5c3 because r3c3 is already in this column. Remove the entry or choose a different digit.

4

3 is blocked from r5c3 by the row

Digit 3 cannot go in r5c3 because r5c9 is already in this row. Remove the entry or choose a different digit.

Sudoku grid illustrating step 4: 3 is blocked from r5c3 by the row — Digit 3 cannot go in r5c3 because r5c9 is already in this row. Remove the entry or choose a different digit.

5

4 is blocked from r5c3 by the column

Digit 4 cannot go in r5c3 because r1c3 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 5: 4 is blocked from r5c3 by the column — Digit 4 cannot go in r5c3 because r1c3 is already in this column. Remove the entry or choose a different digit.

6

5 is blocked from r5c3 by row and column

Digit 5 cannot go in r5c3 because r5c1 is in this row and r7c3 is in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 6: 5 is blocked from r5c3 by row and column — Digit 5 cannot go in r5c3 because r5c1 is in this row and r7c3 is in this column. Remove the entry or choose a different digit.

7

7 is blocked from r5c3 by column and box

Digit 7 cannot go in r5c3 because r8c3 is in this column and r4c2 is in this box. Remove the entry or choose a different digit.

Sudoku grid illustrating step 7: 7 is blocked from r5c3 by column and box — Digit 7 cannot go in r5c3 because r8c3 is in this column and r4c2 is in this box. Remove the entry or choose a different digit.

8

8 is blocked from r5c3 by the column

Digit 8 cannot go in r5c3 because r2c3 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 8: 8 is blocked from r5c3 by the column — Digit 8 cannot go in r5c3 because r2c3 is already in this column. Remove the entry or choose a different digit.

9

1 is blocked from r5c6 by the column

Digit 1 cannot go in r5c6 because r7c6 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 9: 1 is blocked from r5c6 by the column — Digit 1 cannot go in r5c6 because r7c6 is already in this column. Remove the entry or choose a different digit.

10

3 is blocked from r5c6 by the row

Digit 3 cannot go in r5c6 because r5c9 is already in this row. Remove the entry or choose a different digit.

Sudoku grid illustrating step 10: 3 is blocked from r5c6 by the row — Digit 3 cannot go in r5c6 because r5c9 is already in this row. Remove the entry or choose a different digit.

11

4 is blocked from r5c6 by column and box

Digit 4 cannot go in r5c6 because r2c6 is in this column and r4c4 is in this box. Remove the entry or choose a different digit.

Sudoku grid illustrating step 11: 4 is blocked from r5c6 by column and box — Digit 4 cannot go in r5c6 because r2c6 is in this column and r4c4 is in this box. Remove the entry or choose a different digit.

12

5 is blocked from r5c6 by row and column

Digit 5 cannot go in r5c6 because r5c1 is in this row and r6c6 is in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 12: 5 is blocked from r5c6 by row and column — Digit 5 cannot go in r5c6 because r5c1 is in this row and r6c6 is in this column. Remove the entry or choose a different digit.

13

6 is blocked from r5c6 by the column

Digit 6 cannot go in r5c6 because r1c6 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 13: 6 is blocked from r5c6 by the column — Digit 6 cannot go in r5c6 because r1c6 is already in this column. Remove the entry or choose a different digit.

14

7 is blocked from r5c6 by the column

Digit 7 cannot go in r5c6 because r9c6 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 14: 7 is blocked from r5c6 by the column — Digit 7 cannot go in r5c6 because r9c6 is already in this column. Remove the entry or choose a different digit.

15

8 is blocked from r5c6 by the column

Digit 8 cannot go in r5c6 because r3c6 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 15: 8 is blocked from r5c6 by the column — Digit 8 cannot go in r5c6 because r3c6 is already in this column. Remove the entry or choose a different digit.

16

1 is blocked from r5c8 by the column

Digit 1 cannot go in r5c8 because r3c8 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 16: 1 is blocked from r5c8 by the column — Digit 1 cannot go in r5c8 because r3c8 is already in this column. Remove the entry or choose a different digit.

17

3 is blocked from r5c8 by row and column

Digit 3 cannot go in r5c8 because r5c9 is in this row and r9c8 is in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 17: 3 is blocked from r5c8 by row and column — Digit 3 cannot go in r5c8 because r5c9 is in this row and r9c8 is in this column. Remove the entry or choose a different digit.

18

4 is blocked from r5c8 by the column

Digit 4 cannot go in r5c8 because r7c8 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 18: 4 is blocked from r5c8 by the column — Digit 4 cannot go in r5c8 because r7c8 is already in this column. Remove the entry or choose a different digit.

19

5 is blocked from r5c8 by row and column

Digit 5 cannot go in r5c8 because r5c1 is in this row and r1c8 is in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 19: 5 is blocked from r5c8 by row and column — Digit 5 cannot go in r5c8 because r5c1 is in this row and r1c8 is in this column. Remove the entry or choose a different digit.

20

7 is blocked from r5c8 by the column

Digit 7 cannot go in r5c8 because r6c8 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 20: 7 is blocked from r5c8 by the column — Digit 7 cannot go in r5c8 because r6c8 is already in this column. Remove the entry or choose a different digit.

21

8 is blocked from r5c8 by the column

Digit 8 cannot go in r5c8 because r8c8 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 21: 8 is blocked from r5c8 by the column — Digit 8 cannot go in r5c8 because r8c8 is already in this column. Remove the entry or choose a different digit.

22

9 is blocked from r5c8 by the column

Digit 9 cannot go in r5c8 because r2c8 is already in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 22: 9 is blocked from r5c8 by the column — Digit 9 cannot go in r5c8 because r2c8 is already in this column. Remove the entry or choose a different digit.

23

Three cells hold only 2, 6 and 9

These 3 cells contain only candidates 2, 6 and 9 and nothing else.

Sudoku grid illustrating step 23: Three cells hold only 2, 6 and 9 — These 3 cells contain only candidates 2, 6 and 9 and nothing else.

24

The triple claims 2, 6 and 9 in this row

Because these cells must take the three digits 2, 6 and 9 among themselves, no other cell in the row can keep them.

Sudoku grid illustrating step 24: The triple claims 2, 6 and 9 in this row — Because these cells must take the three digits 2, 6 and 9 among themselves, no other cell in the row can keep them.

25

Other cells in row 2, 6 and 9 are targets

Other cells in row 2, 6 and 9 still contain 5 and are removal targets.

Sudoku grid illustrating step 25: Other cells in row 2, 6 and 9 are targets — Other cells in row 2, 6 and 9 still contain 5 and are removal targets.

26

Remove 2, 6 and 9 from the rest of row 5

Remove 2, 6 and 9 from the other cells in row 5.

Sudoku grid illustrating step 26: Remove 2, 6 and 9 from the rest of row 5 — Remove 2, 6 and 9 from the other cells in row 5.

27

Result

Result after applying the technique.

Sudoku grid showing the result after applying the technique

Tips & Patterns

Naked Triples don't require all three candidates in each cell.
Look for cells with 2-3 candidates that share digits.
Example: cells with {1,2}, {2,3}, and {1,3} form a Naked Triple.