The standard dice has opposite sides which sum is always 7. So, if you see the side of a dice with one point (number 1), then the opposite side is with 6 points on it (7-1=6). If if you see the side of a dice with 2 points (number 2), then the opposite side is with 5 points on it (7-2=5). if you see the side of a dice with three points (number 3), then the opposite side is with 4 points on it (7-3=4). if you see the side of a dice with four points (number 4), then the opposite side is with 3 points on it (7-4=3)...and so on.