Mom's Sudoku

Fill every row, column and 3×3 box with the numbers 1 to 9, using each number once.

• Tap a square, then tap a number. Tap the same number again to take it back.
• Turn on Notes to pencil in small numbers you are considering.
• Hint points to a square you can work out next and explains why. It only shows the number if you ask.
• Your game saves itself, and each level keeps its own puzzle.
• On a keyboard: arrows move, 1–9 enter, N for notes, H for hint, U for undo.

• Easy: only needs spotting the one place or one number that fits.
• Medium: also needs locked candidates and pairs.
• Hard: also needs triples or an X-wing.
• Diabolical: also needs a swordfish, XY-wing or XYZ-wing. Pencil notes are all but essential.

No puzzle needs guessing. Each has one solution.