THE OPPOSITE SIDES OF A DICE ALWAYS ADD UP TO SEVEN

WHY IS THIS SO?
-Imagine a transparent cube. It has to have an exact centre. From that centre to each given surface which are six, have to be equally balanced. Each opposite sides, which are two, delivers seven dimples in total in order to make the dice purely balanced in order to make it tumble thus making fair game. 
-Opposite sides of a die traditionally add up to seven, implying that the 1, 2 and 3 faces share a vertex. These faces may be placed clockwise or counterclockwise about this vertex. If the 1, 2 and 3 faces run counterclockwise, the die is called "right-handed", and if those faces run clockwise, the die is called "left-handed". Western dice are normally right-handed, and Chinese dice are normally left-handed.