Hi, Before ask my question, let me explain how this game works. It exist a board with 9 positions and 9 pieces. Each position of the board is for a piece. A piece is composed by four symbols on each side. Each piece must match their neighbors, and each one can rotate. The goal of this game is to put all the pieces in some order, in a way that each piece matches with their neighbor. An example of a final is in attachment. I would like to calculate how many combinations of the pieces exist for a possible the solution?