Its simple to me, everything in this world is based on chance and for that reason someone can win and another can lose simply by making a try. Right on this forum, I have seen a bet site that allows you predict the last number of your transaction id and if you correct, you win big and when you wrong, you lose all. its as simple as that when you are ready for it, just go with for it. But I am sure they will have a particular exchange site to serve as a model for their use...