Use your mouse or keyboard arrows to move the tiles.
Rules of the 15 Puzzle
The 15 Puzzle is a classic sliding puzzle that consists of a 4x4 grid with 15 numbered tiles and one empty space.
- Objective: Arrange the tiles in numerical order from 1 to 15, from left-to-right and top-to-bottom, with the empty space in the bottom-right corner.
- How to Move: You can slide any tile that is horizontally or vertically adjacent to the empty space into that space.
- Winning State: The puzzle is solved when the tiles are in the correct order.
History of the 15 Puzzle
The 15 Puzzle became a worldwide craze in the 1880s. While its exact invention is debated, it was popularized by Noyes Palmer Chapman and later, the famous puzzlist Sam Loyd. Loyd famously offered a $1,000 prize for solving an impossible configuration of the puzzle, which generated immense publicity. The puzzle's solvability is a classic case study in mathematics, specifically in permutation groups, as only half of all possible starting positions are solvable.
Basic Solving Strategy
A common method is to solve the puzzle row by row.
- Solve the Top Row: Get tiles 1, 2, and 3 into their correct positions. Then, maneuver tile 4 into the top-right corner without disturbing the others. This often requires temporarily moving the other top-row tiles.
- Solve the Second Row: Use a similar method to get tiles 5, 6, and 7 in place, followed by 8.
- Solve the Last Two Rows: The final two rows (9-15) are the trickiest. It's often easier to solve the left two columns (9, 13 and 10, 14) first, leaving the last three tiles (11, 12, 15) to be rotated into place.