Sudoku

Medium Sudoku puzzles

Medium puzzles start with about 30 to 35 digits and add one more idea: a digit stuck in one line. When every spot for a digit inside a box lies in the same row or column, that digit can't go anywhere else along it. Notes start to pay off here.

Practice gives you puzzles you haven't solved yet, as many as you like, and keeps your best time without hints. Every puzzle has exactly one solution and can be solved by logic alone.

How to play Sudoku

1. Fill every empty cell with a digit from 1 to 9.
2. Every row, every column and every one of the nine 3×3 boxes holds each digit exactly once.
3. The digits the puzzle starts with stay where they are.

Tap a cell to select it, then tap a digit to write it in. Tap the same digit again to take it out, or use Erase. Turn on Notes to write small pencil marks instead: the digits a cell could still hold. Fill notes writes them all in at once, so you can start crossing digits off. On a keyboard, use the arrow keys to move, 1–9 to write, Shift with a digit for a note, N to switch notes on and off, Backspace to erase and Ctrl+Z to undo.

Solving tips

• Scan the boxes one digit at a time. If a 7 already sits in two of a box's rows and two of its columns, the box has only one cell left where its 7 can go.
• Look for crowded cells. When a cell's row, column and box already hold eight different digits between them, the ninth is the only one it can be.
• Notice digits stuck in one line. If every spot for a 3 inside a box lies in the same row, that box's 3 is in that row, so no other cell of the row can be a 3.
• Find pairs. When two cells of a row can only hold the same two digits, those digits belong to them, and you can cross both off everywhere else in the row.