Slide tiles into the empty square, one at a time, until they are back in order with the gap at the bottom right.
The full guide, with a worked example and common mistakes: How to play Sliding Tiles.
Each slide changes the number of inversions in a fixed way, so a hidden ‘odd or even’ value never changes. Positions with the wrong value can never reach the finished board.
Yes — the hint and the solver search for the fewest moves. For very scrambled 4×4 positions the solver may give a short solution instead if the exact search runs out of time, and says so.
Yes — download a PDF of puzzles with the shortest solutions at the back. Sliding puzzles don’t work on the Slate whiteboard, so there’s no Slate file for this one.
Open the Sliding Tiles Solver, set up your position and press Solve.