Sudoku Step by Step: Solve Your First Full Puzzle

Reading about techniques helps, but watching them applied to a real puzzle is how sudoku finally clicks. Below is a complete beginner puzzle solved step by step, with the reasoning explained at every move.

Setup: Our Puzzle

We'll use a gentle puzzle with plenty of clues. Grab a pencil (or open our sudoku maker and generate an easy puzzle to follow along) and let's begin.

Move 1: Scan the Top Row

Start with the row that has the most clues. In our puzzle, the top row is missing 2, 4, and 9.

• The 2 can't go in column 3 (a 2 is already there) or column 7 (a 2 is there too), so the 2 goes in the remaining open spot.
• The 4 and 9 resolve the same way — check which columns are blocked by the intersecting boxes.

After scanning all three rows in the top band, several cells fill in.

Move 2: Box-First Scanning

Now look at each 3x3 box, one at a time.

The top-left box is missing 1, 5, and 8. Check the columns running through the box:

• The 5 already appears in the second column of the middle band, so the 5 in this box must go in the rightmost column.
• The 1 and 8 are blocked in only one direction each — they fill in cleanly.

Box by box, the top band completes.

Move 3: Hidden Singles in the Middle

With the top band done, look down the columns. In column 4, the digit 3 is missing and only one cell can accept it — a classic hidden single. Every other empty cell in that column is blocked by a 3 in its row or box.

Hidden singles are the most common "aha" moment for beginners. The digit isn't obvious because the cell has many candidates — but once you check, only one spot works.

Move 4: Naked Singles Take Over

As more cells fill, naked singles appear everywhere. A cell in the middle box now has only one possible digit left — write it down. Then that digit unlocks another cell, and another.

This is the satisfying cascade every solver knows: the puzzle suddenly solves itself in a chain reaction.

Move 5: Finish With Scanning

The last few cells are pure scanning. Check every remaining empty cell against its row, column, and box. With the grid nearly full, most cells accept only one value.

The Full Thought Process, Summarized

1. Scan rows and columns with the most clues first
2. Check each box for digits that fit in only one spot
3. Repeatedly fill naked and hidden singles as they appear
4. Re-scan after every pass — each filled cell creates new opportunities

Practice the Same Method

The walkthrough above is exactly the process our hints tool follows when you ask for a nudge — it finds the next logical move and explains it.

To practice: generate an easy puzzle, try to solve it using only scanning and singles, and reach for a hint only when you're truly stuck. After three or four puzzles, the pattern becomes automatic. Then move on to sudoku logic for the techniques that crack hard puzzles.