Probably everyone knows about the famous 15 Puzzle. These are similar puzzles; you slide and rearrange the tiles as requested.

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If the 14 Puzzle at the top is a little bit hard, then try the other ones. If you start from the 2 Puzzle and move onto other ones, you will get the knack of it.

The 15 Puzzle given here is a lot harder than the original 15 Puzzle. It requires quite many number of moves to finish, so it may be better if you move the tiles in your head!