Solution counts at a glance
| Board | Unique solutions | With rotations & reflections |
|---|---|---|
| 6 × 10 | 2,339 | 9,356 |
| 5 × 12 | 1,010 | 4,040 |
| 4 × 15 | 368 | 1,472 |
| 3 × 20 | 2 | 8 |
| 8 × 8, 2×2 centre hole | 65 | 520 |
Every rectangle has 4 symmetries (itself, flipped left to right, flipped top to bottom, and turned 180°), so each unique solution appears 4 times among all placements.
The first 6×10 solution
The letters name the pieces: F, I, L, N, P, T, U, V, W, X, Y and Z. Each letter appears exactly once, covering 5 squares.
The two 3×20 solutions
The 3×20 strip has only two solutions, which makes it the hardest of the four rectangles to find by hand. Here is the first one; open the 3 × 20 tab above to see both.
Solve one yourself
- Learn the opening moves in how to solve pentomino puzzles.
- Check a partial idea with the pentomino solver, which also handles 8×8 boards with any four holes.
- Prefer playing? Try the free 8×8 packing puzzle with 100 levels.