---
title: "Full House: One gap, one missing digit"
description: "A Full House has just one empty cell in a row, column or 3×3 box. The one missing digit belongs in that cell."
lang: "en"
canonical: "https://unisu-sudoku.app/en/sudoku-techniques/full-house/"
---

[Back to the learning guides](https://unisu-sudoku.app/en/learn/)

Fundamentals

# Full House: One gap, one missing digit

A Full House has just one empty cell in a row, column or 3×3 box. The one missing digit belongs in that cell.

![Unisu lesson on Full House, showing the explained grid](https://unisu-sudoku.app/_astro/en.Bnh-GLbv_INnQn.webp)

A Full House has just one empty cell in a row, column or 3×3 box. The one missing digit belongs in that cell.

## An example from the app

Look at the highlighted row. Eight cells are filled and only one is empty.

The digits 1, 2, 3, 4, 5, 6, 8 and 9 are already there. The missing digit is 7. Only 7 can complete this row.

## Practice the next step

With several empty cells, you need more information. Knowing the missing digits alone does not assign their positions.

In the app, follow the reasoning in the matching lesson and try a task yourself. With a new puzzle, always start from its actual candidate state.

## Questions about Full House

### Where can a Full House occur?

In a row, column or 3×3 box. That area must have just one empty cell.

### How do I find the missing digit?

Compare the digits present with 1 through 9. The only missing digit goes in the remaining cell.

### Do I need candidate notes?

Not necessarily. The eight digits already present determine the missing ninth digit.

### Is a row with two empty cells a Full House?

No. Knowing the two missing digits alone does not determine which cell each belongs in.

### How does Full House differ from Naked Single?

Full House uses an area’s only empty cell. Naked Single uses a cell’s only candidate, even when its surrounding areas have several gaps.

## Keep practicing in Unisu

Download Unisu for iPhone or Android. Solve a puzzle or work through a guided lesson on the technique.

-   [Download on the App Store](https://apps.apple.com/us/app/id6775824061?l=en)
-   [Get it on Google Play](https://play.google.com/store/apps/details?id=app.unisu.sudoku&hl=en)

## Useful before this guide

### How to play Sudoku: rules and your first move

[Read more: How to play Sudoku: rules and your first move](https://unisu-sudoku.app/en/sudoku-rules/)

## Where to go next

Fundamentals

Unisu · Oct 27, 2026

### [Naked Single: One candidate left in a cell](https://unisu-sudoku.app/en/sudoku-techniques/naked-single/)

A Naked Single is a cell with exactly one candidate remaining. Its row, column and box rule out every other digit.

Unisu

### [Learn Sudoku: a path from rules to techniques – Unisu](https://unisu-sudoku.app/en/learn/)

Start with the rules, get comfortable with pencil marks and choose a technique for the situation you’re working on.

Download app

## Ready for a puzzle? Take a moment.

Download Unisu on your phone. Start a Sudoku or choose a lesson on the technique you want to understand.

-   [Download on the App Store](https://apps.apple.com/us/app/id6775824061?l=en)
-   [Get it on Google Play](https://play.google.com/store/apps/details?id=app.unisu.sudoku&hl=en)

![The daily challenge in Unisu](https://unisu-sudoku.app/_astro/en.C-sYR9hJ_1QwI9G.webp)

![A classic Sudoku game in Unisu](https://unisu-sudoku.app/_astro/en.C6DJ1kiE_2dRWDN.webp)