New: Kerb Clash, clear the jammed car parkNew: Sudoku and Minesweeper, classic puzzles that play offlineInstall any game to your home screen

Futoshiki: One Place Left (Hidden Singles)

When a number can only go in one square of a row or column, it goes there, even if that square could still be other numbers.

Open Futoshiki full screen for more sizes, saved progress and best times.

This is one of the Futoshiki techniques, each shown on the same 7×7 from the game, Hard level 5.

The rule

  1. Pick a row or column, and a number it still needs.
  2. For each empty square in it, ask: could this number go here? Not if the square’s other line already has it, and not if a sign rules it out.
  3. If only one square is left, the number goes there.

In a real puzzle

On the 7×7, it’s first needed at step 19. Column 3 still needs its 2, and by now only one square in the column has a 2 in its notes: row 6. So that’s where the 2 goes, even though the notes leave that square other options.

Step 19: one place left in column 3 Column 3's notes. Only one square in the column still has a 2 in its notes, row 6, so the 2 goes there. 1 3 4 5 6 2 7 5 6 2 4 5 1 1 2 3 4 2 7 3 4 5 1 2 3 4 5 6 7 1 2 3 4 5 6 7
Step 19: column 3’s notes. Only row 6 can still take the 2.

How often you’ll need it

On 43 of the 50 Easy levels, 48 Medium and every Hard one: 1.8 times per Easy level on average, 4.0 on Medium and 8.6 on Hard. It’s 6 of the 57 moves on the 7×7 here.

Next steps

Questions

Why can't I see these?

Because you have to look at a number rather than a square. Pick a row or column, pick a number it still needs, and check each empty square in turn. Notes make it much quicker.