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.
The object is to have a hand with a total value higher than the dealer's without going over 21. Kings, Queens, Jacks and Tens are worth a value of 10. An Ace has the value of 1 or 11. The remaining cards are counted at face value.