Sudoku

How to play

1. Fill the grid so every row, every column and every 3×3 box contains the digits 1 to 9 exactly once.
2. Select a cell, then tap a number. Switch on Notes to pencil in candidates instead.
3. The Daily puzzle is the same for everyone on a given UTC day. Easy, Medium and Hard start a new random puzzle.
4. Every puzzle has exactly one solution, so it can always be solved by logic without guessing.

Tips and strategy

• Start with numbers that already appear many times; their remaining spots are easiest to pin down.
• Scan each box for a digit that can only fit in one cell (a hidden single).
• Use notes once the obvious cells are done, and look for cells with only one candidate left.
• If a conflict is highlighted, one of the highlighted digits is wrong; trace back to the last guess.