sudokUI › Sudoku techniques › Full House
Full House in sudoku
naked and hidden single at once · how it fits
A row, column or box has eight of its nine cells filled, leaving exactly one empty cell.
Why it works
A unit must contain each digit from 1 to 9 exactly once, so the one digit missing from the eight filled cells is placed in the empty cell.
How to spot it
Scan for a row, column or box with eight digits filled in, then work out which digit from 1 to 9 is absent.
Worked example
Full House: r4c9 is the last empty cell in row 4, so it must be 8.
Practise it on a real puzzle. sudokUI generates a puzzle that needs Full House and takes you straight to the position where it applies. Hints draw the pattern on the board and explain the step.
In a puzzle's rating
Each time the solver needs Full House, the puzzle's difficulty rating grows by 4. Its class is Beginner. It is needed in every puzzle that sudokUI generates. How the rating works.