Sudoku Solving Techniques
New to Sudoku? Learn how to play with an interactive puzzle in the how to play guide 🔗
To get you started with solving your first puzzle, there are two intuitive techniques that you can use: scanning and elimination.
Quick Terminology: a cell is a single square in the grid, a house is a 3x3 group of cells. In Not Evil Sudoku, the houses are grouped together and you can see them clearly below. There are a total of 9 houses in a 9x9 grid.
Scanning
The most basic technique is scanning - systematically looking for possible numbers that can go in each empty cell.
Here, we can see that in the first house one of the missing numbers is a 3.
If we scan the first row, we spot a 3 in the third house!
Thus, the first blank cannot be a 3 since we can only have one 3 in each row. So, our second blank must be a 3.
If we scan the first row, we spot a 3 in the third house!
Thus, the first blank cannot be a 3 since we can only have one 3 in each row. So, our second blank must be a 3.
In Not Evil Sudoku, you can enable highlighting all instances of a selected number to help you scan the board.
Settings: Advanced → Highlighter
Similarly, in the second row of houses, we can scan the rows to see where the 3s are.
We see that the 3s are in the fifth and sixth rows of our puzzle.
So, the 3 of the first house must be in the fourth row of our puzzle in the only available spot.
We see that the 3s are in the fifth and sixth rows of our puzzle.
So, the 3 of the first house must be in the fourth row of our puzzle in the only available spot.
Scanning is not limited to rows, we can also scan columns!
Now that we filled in the 3s of the first two houses in our first column of houses, we can turn our attention to the last house.
Scanning the columns, we see that the 3 of the last house in our column must be in the first column and third row.
Now that we filled in the 3s of the first two houses in our first column of houses, we can turn our attention to the last house.
Scanning the columns, we see that the 3 of the last house in our column must be in the first column and third row.
Elimination
Elimination is a very simple technique. We scan a row/column/house and see what numbers are missing.
Here, we can see that the numbers 1, 6 and 8 are missing in the first row of our puzzle.
But if we look at the last cell of our row, we can scan the column to see that both 1 and 8 are in the column. Therefore, the only missing number that could go in the cell of our first row is a 6!
Here, we can see that the numbers 1, 6 and 8 are missing in the first row of our puzzle.
But if we look at the last cell of our row, we can scan the column to see that both 1 and 8 are in the column. Therefore, the only missing number that could go in the cell of our first row is a 6!
In Not Evil Sudoku, you can configure notes to help you keep track of possible numbers for each cell.
Settings: Notes
Each time you use a technique, more of the board is revealed and new opportunities arise!