Summary: Fill a 9×9 Sudoku so each row, each column, and each 3×3 box contains the digits 1 through 9 exactly once. Then a Very Easy example shows the first fills: start in a nearly-full 3×3 box, then finish a row the same way. Looking up a variant? Jump to Dot Sudoku, Hyper Sudoku, or Multidoku.
What a Very Easy 9×9 Sudoku Looks Like
A Sudoku grid is 81 cells, grouped into nine 3×3 boxes. The printed starting digits stay where they are. You only write in the empty cells.
Left is the puzzle. Right is the finished solution. Cover the right-hand grid while you work the left-hand grid. Count rows down from the top and columns left to right. The first fills are walked below.
Sudoku Rules: Rows, Columns, and 3×3 Boxes
- Each row holds 1–9 once. A digit that is already in a row cannot go in any other cell of that row.
- Each column holds 1–9 once. Same rule, read up and down.
- Each 3×3 box holds 1–9 once. The thick lines mark the nine boxes. A digit that is already in a box cannot go in any other cell of that box.
- Printed starting digits do not move. They are already part of the answer. Do not erase or overwrite them.
- One correct filling. Do not guess. A finished 9×9 in this guide has one correct filling.
How to Play Sudoku: First Fills on a Very Easy 9×9
Work the left-hand Very Easy board.
- Start with a box that is almost full (two-empty test). Reading the top-left box left to right, top to bottom, the printed digits are 9, 5, 1, 2, 4, 6, and 8. The two empty cells are row 1, column 1 and row 2, column 3. The digits 1–9 minus those seven leave 3 and 7. The top-left empty sits in a row that already has a 3 (row 1, column 7), so that empty cannot be 3. Write 7 in row 1, column 1.
- Finish that box. The last empty cell in the top-left box is row 2, column 3. Step 1 already used the 3 in row 1 to place 7, so this last empty is the leftover 3.
- Stay on that row. Row 2 now reads 1, 2, 3, 9, 5, 7, 4, blank, blank. It still needs 6 and 8. Column 8 already has an 8 in row 4, so row 2, column 8 cannot be 8. Write 6 in row 2, column 8. The last empty in that row (row 2, column 9) is 8.
- Then take another row that is almost full. Row 7 reads 2, 3, blank, 6, 4, 8, 9, blank, 5. It still needs 1 and 7. Column 8 already has a 1 in row 1, so row 7, column 8 cannot be 1. Write 7 in row 7, column 8. The remaining empty in that row (row 7, column 3) is 1.
Those fills are row 1 column 1 = 7, row 2 column 3 = 3, row 2 column 8 = 6, row 2 column 9 = 8, then row 7 column 8 = 7 and row 7 column 3 = 1. When a box, row, or column has only one empty cell, that cell is the missing digit.
Your turn — same two-empty test. Keep the six fills you just wrote. Cover the right-hand grid. The top-right box should now have two empties (row 1, column 9 and row 3, column 8) and still need 2 and 5. Look down the whole of column 9 — not just the three cells in this box — to pick which of 2 or 5 goes in row 1, column 9, then finish that box. Uncover the right-hand grid to check those two cells. Cover it again. Then find the next box, row, or column with only one or two empties, and keep going.
Dot Sudoku
Dot Sudoku uses the same 9×9. Nine extra cells are shaded gray (not shown on the figure above). Those nine cells are one more group that must hold 1–9 exactly once. If that gray set already shows seven digits, the two empty gray cells are the two missing digits. Use a row or column that already shows one of the two missing digits, the same way row 1’s 3 placed the 7.
The gray cells follow a printed pattern — box centers, corners, or an asterisk — or they are extra shaded empties (Random Dots). On a patterned page the gray set is one more 1–9 group. Use it the same way you used a box.
Hyper Sudoku
On a classic 9×9, four extra gray 3×3 windows sit one cell in from each corner (not the corner boxes themselves). Each window must hold 1–9 exactly once. The usual rows, columns, and 3×3 boxes still apply.
Those windows overlap the regular boxes. A digit already sitting in a gray window cannot go in any other cell of that window. If a gray window already shows seven digits, the two empty window cells are the two missing digits. Use a row or column that already shows one of the two missing digits, the same way row 1’s 3 placed the 7.
Multidoku
A Multidoku page is two or more classic 9×9 grids that overlap — Twins is two overlapping 9×9s; Samurai is five 9×9s that share cells. Each grid still needs 1–9 once in every row, column, and 3×3 box. A shared cell has to fit every grid it sits in.
Fill a nearly-full box in one 9×9 the same way. If the cell you just wrote sits in the overlap, that same digit has to fit the other grid’s row, column, and box too.
Start a Printed 9×9 Sudoku the Same Way
You can start any Very Easy 9×9 from a nearly-full box, row, or column and fill without guessing. Once that is clear, Dot and Hyper add extra groups that also hold 1–9 once, and Multidoku uses the same rule on overlapping grids. Want to make a set? See Getting Started with Puzzle Maker Pro Sudoku.
Try It Online
Sudoku in the browser is the same fill: click an empty cell and type a digit. Printed starting digits stay put. Click a wrong digit and delete it; printed starting digits will not clear.
Play a classic 9×9 Sudoku: [/puzzles/classic-sudoku/ – confirm].
FAQ
How do you play Sudoku?
Fill the empty cells so each row, each column, and each 3×3 box holds the digits 1–9 exactly once. Start in a box, row, or column that is almost full.
How do Dot Sudoku, Hyper Sudoku, and Multidoku change the board?
Classic 9×9 rules still apply. On a patterned Dot page, one extra group of nine shaded cells also holds 1–9 once. Hyper Sudoku adds four extra 3×3 windows with the same extra rule. Multidoku overlaps two or more 9×9 grids; a shared cell has to fit every grid it sits in.
Can I change the printed starting numbers?
No. Those printed digits are already part of the solution. Fill only the empty cells.
Does a page with letters or pictures use different rules?
No. Roman numerals, letters, and pictures stand in for 1–9. Each symbol still appears once per row, column, and box.
Does every Sudoku have one solution?
A finished 9×9 in this guide has one correct filling. If two cells both look legal for the same digit, one of those placements will break a row, a column, a box, or — on Dot, Hyper, or Multidoku — the extra group that cell sits in.
Where should I start on a new page?
Look for a box, row, or column that is almost full — only one or two empties. The Very Easy board above opens in the top-left box, which already showed seven of the nine digits. On Dot or Hyper, a nearly-full gray group works the same way.