Andoku Sudoku 3 is the best offline sudoku app for Android users. It has 10,000 puzzles with six variations of sudoku and eight levels of difficulty. There are also autosave features, automatic error checking, and pencil mark compatibility.
Sudoku techniques
1
Scanning in one direction: In our first example we will focus on box 2, which like any other box in Sudoku must contain 9. ...
2
Scanning in two directions: ...
3
Searching for Single Candidates: ...
4
Eliminating numbers from rows, columns and boxes: ...
5
Searching for missing numbers in rows and columns: