# Conway puzzle

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Pieces used in the Conway puzzle, one of each kind.

Conway's puzzle, or Blocks-in-a-Box, is a packing problem using rectangular blocks, named after its inventor, mathematician John Conway. It calls for packing thirteen 1 × 2 × 4 blocks, one 2 × 2 × 2 block, one 1 × 2 × 2 block, and three 1 × 1 × 3 blocks into a 5 × 5 × 5 box.[1]

## Solution

A possible placement for the three 1×1×3 blocks. The vertical block has corners touching corners of the two horizontal blocks.

The solution of the Conway puzzle is straightforward when one realizes, based on parity considerations, that the three 1 × 1 × 3 blocks need to be placed so that precisely one of them appears in each 5 × 5 × 1 slice of the cube.[2] This is analogous to similar insight that facilitates the solution of the simpler Slothouber–Graatsma puzzle.

## References

1. ^
2. ^ Elwyn R. Berlekamp, John H. Conway and Richard K. Guy: winning ways for your mathematical plays, 2nd ed, vol. 4, 2004.