1Definition: A simple technique for entering a Big Number when there is only one possible number that can go in a cell.
2Look For: Cells which have houses containing 8 different Big Numbers.
3Consequence: The ninth (missing) number can be entered in the cell.
4Why it Works: When there are eight different numbers in a cell's house, the number for the cell must be the remaining number that is missing from the house.
6Since it is difficult to immediately spot a house with 8 different numbers in it, look for empty cells at the intersection of many filled cells. Then, scan the cell's house for the sequence 1-9. If you find all of the numbers but one, then the cell in question has only a single possibility: the missing number from the sequence.
7When using the SueDoku interface, it can be helpful to enable the Highlight House on Hover feature from the Tools menu. As shown in the figure above, this highlights all of the numbers in the house.
8In our example there is a single possibility for cell I5. Looking at its house (row 5, column I, and block 6), we see all numbers accounted for except for number 7. So, we enter Big Number 7 in I5.
9Your Turn! Now it's your turn to try one! We just created a new single possibility in the cell directly above this one (i.e. I4.) Enter the missing number for that cell.
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