Full House
One empty square remains in a row, column or box. The missing digit belongs there.
What it is
A Full House — also called a last cell — is the easiest Sudoku moment: one row, column or box has eight digits and one gap. Because every unit contains each digit from 1 to 9 exactly once, the missing digit must go into that gap.
How to spot it
After every placement, glance at its row, column and box. Do you see just one empty square? Read the eight visible digits, find the one that is absent and place it. There is no candidate list or guesswork needed.
Worked example
One question per step: follow the highlighted column.
Step 1 of 4: Look at the highlighted column
It has exactly one gap. A completed column contains every digit from 1 to 9 once.
Why it matters
Full Houses are quick, certain progress. One simple placement often creates the next one nearby, so this habit keeps an easy puzzle flowing and clears space for harder patterns later.
Practise now
Solve a puzzle where this technique decides the game
Frequently asked questions
Is a Full House the same as a Naked Single?
Almost, but not quite. A Full House is defined by a unit having one gap. A Naked Single is defined by a cell having one candidate. Every Full House is also a Naked Single, but a Naked Single can appear in a unit with several empty cells.
When should I look for Full Houses?
Immediately after every placement. It takes seconds and often starts a chain of easy placements, especially towards the end of a puzzle.
Put it to use
Where you will meet it
This pattern is the backbone of easy grids. Start one and you will use it within a few moves.
Play EasyStuck on a grid of your own?
Type the position into the solver and it walks the whole solution, naming the technique behind every step — including this one.
Open the solverPrefer paper? Ready-made Easy sets as a PDF.Print puzzles
Finished reading? Mark it done and the learning path remembers where you got to.