Turning the coin upside down or upside down is a geometric probability. Face up or face down, unless manually manipulated, the probability of face up or face down is the same, that is, 50% each, and there is no problem that face up is more than face down or face down is less than face down. This is the view of equal probability. Of course, if you manipulate it manually, the probability of facing up can be changed, but that is not a fair operation. If you explore fairly, the probability of facing up is 50%.