 The position of the played tile may be either to the right or left of the adjacent tiles for a horizontally-oriented equation (representing either 10 = 8 + 2 or 8 + 2 = 10), or either above or below the tiles for a vertical orientation.Each time a player places a tile, the move is considered final and irreversible.Other players may challenge the move if the tile is not a solution using proper arithmetic.