To start a standard Sudoku, fill the empty squares so each row, each column and each 3 × 3 box contains the numbers 1 through 9 once. Begin with easy puzzles and look for a place where only one number can fit. You do not need arithmetic or fast mental calculation.
Learn the three checks
Every placement must work in three directions: across its row, down its column and inside its outlined box. A number that fits the row can still be wrong if it already appears in the column or box.
Before writing a number permanently, pause and check all three. This simple habit prevents many mistakes that otherwise become difficult to untangle later.
Find your first move by elimination
Choose a row with several numbers already filled. Write down the missing numbers on scrap paper. For each empty square, cross out any candidate that appears in that square's column or box.
Use Sudoku 001 below for a real first move. Look at the top-right square: row 1, column 9. Row 1 is missing 2, 4, 7, 8 and 9. Column 9 already contains 4, 7 and 8, and the top-right 3 × 3 box already contains 2. That leaves only 9 for the square.
This is a single-candidate move, so no guessing is needed. After placing 9, check the affected row, column and box again; one confirmed number can narrow another square.
Try a digit-by-digit scan
Another starting point is to choose a digit, such as 1, and look for its existing positions across a row of three boxes. Those positions rule out places where another 1 could go. Continue only when the restrictions leave a single valid square in a box.
If more than one position remains, leave it undecided. Being able to narrow the choices is useful even when it does not immediately produce an answer.
Keep candidates small and temporary
Use light pencil marks for possibilities and a clear full-size number for a confirmed placement. Remove outdated candidates when new numbers affect the same row, column or box.
If the page becomes crowded, work on just one area at a time. A fresh easy puzzle may be a better next step than trying to rescue an unclear collection of notes. There is no timer to beat.
What to do when you get stuck
- Check recent entries for a duplicate in a row, column or box.
- Revisit the fullest rows and columns; they often need fewer candidate checks.
- Look at a different region of the grid.
- Take a break if you are no longer enjoying it.
- Use the answer page to verify one suspect entry, then cover it again if you want to keep solving.
An answer page can help you check your work. It does not need to become a race to copy the finished grid. If a solution surprises you, trace back which row, column or box ruled out the other numbers.
Print an easy puzzle before printing a book
Download the free four-page adult puzzle sample to try the Sudoku preview on page 3; its answer companion is on page 4. The file reproduces our current product previews with added answer companions, not the complete paid downloads. Print that page first and check whether the number size and layout suit you. No email signup is required.
Want to try one puzzle first? The free 12-page printable starter pack includes an easy Sudoku and its answer, alongside planning and family activities. No purchase or email signup is required.
The Printable Sudoku Book contains 200 puzzles: 60 Easy, 70 Medium and 70 Hard. Each has exactly one solution. There are 200 puzzle pages and 50 answer pages, with one puzzle per page and four solutions per answer page.
The PDFs are US Letter files inside a ZIP. Extract the download, open the PDF and print the individual page you want. Check one test print for readable numbers and uncut margins before printing a larger selection. Download and printing help explains the basic steps.
If you want several kinds of paper activities, the Sudoku book is also in the Coloring & Activity Mega Bundle. Compare what is included before buying so you do not purchase the same book twice.