Sudoku

Every row, every column and every 3×3 box must hold each number from 1 to 9 exactly once. The dark numbers are part of the puzzle and cannot change.

Tap an empty square, then tap a number to put it there. Tap the same number again to take it out, or use Erase.

Not sure yet? Turn on Notes and the number goes in orange, as a "maybe." Notes never count as mistakes. When you are sure, turn Notes off and put the number in as your answer.

Tips: tapping a square highlights its row, column and box, and every square with the same number. Hint fills in one square for you. Undo takes back as many moves as you like. Your puzzle is saved on this device, so you can come back to it later. On a computer you can also type the numbers and move with the arrow keys.