Full House
- Column 2: only one cell is empty.
- Column 2: the only missing number is 7.
Sudoku solving techniques
These are the techniques the hint in our Telegram game can name, easiest first. Each is shown on a real puzzle in the hint's own words, with a puzzle that calls for it to practice on.
Or scan with your phone
Easy
Naked Single
- Look at the numbers in the row, column and box of this cell.
- Every number except 8 is already used there.
- So this cell must be 8.
Master
Pointing
- Box 5: 6 fits only in the highlighted cells.
- Row 6: all the highlighted cells lie in it.
- Row 6: so 6 can go nowhere else.
Claiming
- Row 3: 3 fits only in the highlighted cells.
- Box 2: all the highlighted cells lie in it.
- Box 2: so 3 can go nowhere else.
Naked Pair
- Row 2: the highlighted cells can hold only 5 and 7.
- Each of 5 and 7 must take one of these cells.
- Row 2: so 5 and 7 can go nowhere else.
Naked Triple
- Row 7: the highlighted cells can hold only 3, 6, and 7.
- Each of 3, 6, and 7 must take one of these cells.
- Row 7: so 3, 6, and 7 can go nowhere else.
Extreme
Naked Quad
- Box 3: the highlighted cells can hold only 5, 6, 7, and 8.
- Each of 5, 6, 7, and 8 must take one of these cells.
- Box 3: so 5, 6, 7, and 8 can go nowhere else.
X-Wing
- In the highlighted lines, 6 fits only in the highlighted cells.
- Whichever cells take 6, each crossing line gets one of them.
- So 6 can go nowhere else in the lines that cross them.
Swordfish
- In the highlighted lines, 7 fits only in the highlighted cells.
- Whichever cells take 7, each crossing line gets one of them.
- So 7 can go nowhere else in the lines that cross them.
Skyscraper
- Look at the highlighted cells.
- Look at their notes: whichever way they are filled, the same notes are ruled out.
- So 7 can be removed from the crossed-out cells.
2-String Kite
- Look at the highlighted cells.
- Look at their notes: whichever way they are filled, the same notes are ruled out.
- So 5 can be removed from the crossed-out cells.
XY-Wing
- Look at the highlighted cells.
- Look at their notes: whichever way they are filled, the same notes are ruled out.
- So 2 can be removed from the crossed-out cells.
Beyond the levels
No level of the game needs these techniques. Their practice puzzles are harder than its hardest level.
Jellyfish
- In the highlighted lines, 2 fits only in the highlighted cells.
- Whichever cells take 2, each crossing line gets one of them.
- So 2 can go nowhere else in the lines that cross them.
XYZ-Wing
- Look at the highlighted cells.
- Look at their notes: whichever way they are filled, the same notes are ruled out.
- So 9 can be removed from the crossed-out cells.
W-Wing
- Look at the highlighted cells.
- Look at their notes: whichever way they are filled, the same notes are ruled out.
- So 4 can be removed from the crossed-out cells.
Finned X-Wing
- In the highlighted lines, 3 fits only in the highlighted cells.
- Whichever cells take 3, each crossing line gets one of them.
- So 3 can go nowhere else in the lines that cross them.
Finned Swordfish
- In the highlighted lines, 5 fits only in the highlighted cells.
- Whichever cells take 5, each crossing line gets one of them.
- So 5 can go nowhere else in the lines that cross them.
Unique Rectangle
- Look at the highlighted cells.
- Look at their notes: whichever way they are filled, the same notes are ruled out.
- So 2 and 7 can be removed from the crossed-out cells.
Contradiction
- Suppose this cell held 7.
- Then these numbers follow, one after another, until a contradiction.
- So 7 is not possible here.