Last Digit / Full House
This method is very easy to recognize and to solve.
Have a look at box #7 highlighted in the Sudoku here.
You can see that there's only one empty cell - R7C2.
All the other cells in this box are filled and contain all the digits '1'-'9', except for '7'.
The Basic Rule of Sudoku says that every house must contain all the digits '1' through '9' -
therefore R7C2 has to be '7' because it's the only missing digit from this box.
All the other cells in this box are filled and contain all the digits '1'-'9', except for '7'.
This scenario is called a full house - it means that all the cells are filled in within a house except for one.
You can be certain which digit should be in that one cell, since a house always contains all the digits '1' till '9', one time each.
Here's another example of a full house, this time it's in row number 6.
Can you see which digit should be in R6C4?
It definitely must be '8', since that's the only missing digit in row 6.
A Full house can be found in a row, column and box.
