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 ÃÂ 2 ÃÂ 4 blocks, one 2 ÃÂ 2 ÃÂ 2 block, one 1 ÃÂ 2 ÃÂ 2 block, and three 1 ÃÂ 1 ÃÂ 3 blocks into a 5 ÃÂ 5 ÃÂ 5 box.
The solution of the Conway puzzle is straightforward once one realizes, based on parity considerations, that the three 1 à1 à3 blocks need to be placed so that precisely one of them appears in each 5 à5 à1 slice of the cube. This is analogous to similar insight that facilitates the solution of the simpler SlothouberâÂÂGraatsma puzzle.