Every Sudoku can be solved with a handful of tricks. Here they are, from the first one you'll use to the ones that crack hard puzzles. Our hint button names these same tricks when it shows you a move.
Look at one empty square. Read off every number in its row, column and box. If eight different numbers are already there, the square must be the ninth. Easy puzzles are mostly this.
Look at one row, column or box and one missing number. If only one empty square there can take it, that's where it goes, even if the square itself could hold other numbers. Medium puzzles lean on this heavily, so scan box by box for each number.
Sometimes inside a box, a number can only go in squares that sit on the same row. You don't know which square yet, but you do know the number is in that row inside this box. So you can rub it out of that row everywhere else. It works the other way too: if in a row a number can only sit inside one box, rub it out of the rest of that box.
Naked pair: two squares in the same row (or column, or box) whose notes are exactly the same two numbers, say 3 and 8. Those two squares will take the 3 and the 8 between them, so no other square in that row can be 3 or 8.
Hidden pair: two numbers that can only go in the same two squares of a row. Those squares must hold those two numbers, so any other notes in them can go.
A triple is the same idea as a pair with three squares and three numbers. An X-Wing happens when a number can only go in two squares in each of two rows, and those squares line up in the same two columns. The number must sit on opposite corners of that rectangle, so you can remove it from the rest of both columns.
This one needs at least one pair or pointing step. Fill in notes first.
| 8 | 9 | |||||||
| 4 | 3 | 8 | ||||||
| 7 | 6 | 2 | ||||||
| 5 | 6 | 2 | 8 | |||||
| 6 | 5 | |||||||
| 4 | 7 | 9 | 1 | |||||
| 4 | 1 | 9 | ||||||
| 6 | 8 | 7 | ||||||
| 3 | 4 |
| 4 | 2 | 8 | 5 | 1 | 7 | 3 | 6 | 9 |
| 5 | 9 | 6 | 2 | 4 | 3 | 7 | 8 | 1 |
| 1 | 7 | 3 | 6 | 8 | 9 | 5 | 2 | 4 |
| 7 | 5 | 9 | 1 | 6 | 2 | 8 | 4 | 3 |
| 6 | 1 | 2 | 4 | 3 | 8 | 9 | 7 | 5 |
| 8 | 3 | 4 | 7 | 9 | 5 | 2 | 1 | 6 |
| 2 | 4 | 7 | 3 | 5 | 1 | 6 | 9 | 8 |
| 9 | 6 | 5 | 8 | 7 | 4 | 1 | 3 | 2 |
| 3 | 8 | 1 | 9 | 2 | 6 | 4 | 5 | 7 |
| Level | Starting numbers | Tricks you need |
|---|---|---|
| Easy | 36 to 38 | Last possible number, only place |
| Medium | 27 to 32 | The same two, but you'll have to hunt for them |
| Hard | 22 to 30 | Pointing and pairs, sometimes triples or X-Wing |
Cross-hatching for the only place a number can go in a box (a hidden single). It solves most easy and medium puzzles on its own.
When a full scan of 1 to 9 finds nothing new. Hard puzzles usually need notes from early on.
Not on PuzzleMint. Our hard puzzles are checked to be solvable with pointing, pairs, triples and X-Wing at most.