The 9x9 grid
Every puzzle uses the same structure: nine rows, nine columns, and nine smaller 3x3 boxes.
How To Play Sudoku
Sudoku is a number-placement puzzle where logic matters more than speed.
How Sudoku Works
The goal is to fill a 9x9 grid so that every row, every column, and every 3x3 box contains the numbers 1 through 9 exactly once. Some numbers are given at the start, and those clues help you work out the rest.
Given clues
The starting numbers are fixed. They give you enough information to solve the rest of the puzzle by logic alone.
5
7
1
7
1
8
1
8
5
5
7
1
4
6
5
7
1
9
5
9
1
4
2
4
9
3
8
1
9
How To Start
A good way to begin is to scan one row, column, or box at a time and look for the numbers that are missing. From there, rule out positions that are already blocked by the same number elsewhere in the grid. Often, progress comes from eliminating impossible options until only one square makes sense.
Simple Solving Tips
Start with rows, columns, or boxes that already contain a lot of numbers. These are usually the easiest places to spot a missing value. If only one square can take a certain number, fill it in and then scan the surrounding row, column, and box again.
Worked Example: One Missing Number
In this example board, the highlighted row already contains 8, 2, 5, 4, 6, 7, 1, 3 and just one square is still empty. Because 9 is the only number missing from that row, the final highlighted square must be 9.
8
2
5
4
6
7
1
3
?
6
1
3
8
5
1
9
2
5
6
5
6
4
3
1
6
4
9
2
5
9
1
2
8
7
4
5
7
4
9
3
4
6
1
3
8
9
3
5
2
7
6
This is often the first kind of fill you spot on an easier puzzle.
Worked Example: Combine Row, Column, and 3x3 Box Checks
Here the answer takes one more step. In the amber middle 3x3 box, the two open squares on the blue row must be 3 and 5. The green column rules out 3 for the red square, so the red square must be 5.
3
6
8
1
2
6
2
1
9
3
9
8
4
2
6
8
7
6
1
4
3
4
2
8
?
7
1
1
3
9
2
4
5
6
5
3
2
8
2
7
1
9
5
3
2
8
1
7
Cross-checking like this is one of the most useful habits in regular sudoku.
Worked Example: Narrow One Square Inside the 3x3 Box
In the highlighted 3x3 box, the missing numbers are 1, 6, 7, and 8. In the red square's row, 1 and 7 are already used. In its column, 8 is already used. That leaves 6, so the red square must be 6.
5
3
4
6
7
8
9
1
2
6
7
2
1
9
5
3
4
8
1
9
8
3
4
2
5
6
7
8
5
9
7
6
1
4
2
3
4
2
6
8
5
3
7
9
1
7
1
3
9
2
4
8
5
6
9
?
5
3
7
2
8
4
2
4
1
9
6
3
5
3
4
5
2
8
6
1
7
9
This is a useful box-based deduction: start with the missing numbers in the 3x3 box, then test one square against its row and column until only one number still fits.
If you are new to sudoku, start with easier boards and focus on consistency rather than guessing. Look for obvious singles first, then revisit rows and boxes that have become easier after each correct placement. The puzzle usually opens up a little at a time.
When a board feels stuck, slow down and check the structure again. The most useful habit is patience: spotting one correct placement often reveals the next. With practice, the rhythm of checking rows, columns, and boxes becomes much more natural.
Good Habits
Avoid guessing if you can help it. Sudoku is most satisfying when each step is justified by the structure already in front of you. If progress slows, move to a different part of the board and come back later with fresh eyes.