Sudoku

Fill every empty square with a number from 1 to 9. Each row, each column and each of the nine 3 by 3 boxes must have every number exactly once.

Tap a square, then tap a number below. Tap Erase to clear a square. The numbers that came with the puzzle are in bold and cannot be changed.

There is no timer and nothing to lose. Undo as many times as you like. Hint tells you a square you can fill in next, and why. If a number repeats in a row, column or box, the game tells you. Notes lets you pencil in small numbers.