How does gambling work in terms of probability theory? Let's see if it obeys mathematics. When a coin is tossed, any of its sides can fall out with the same probability. There are only two possibilities - heads or tails. The probability of falling heads is ½ (50%), that is, half of the cases will come up tails. Probability shows how often the expected result can be achieved and can be represented as the ratio of the expected outcomes to the total number of all possible outcomes over a sufficiently long period of time and with a large number of repetitions. The probability of an event reflects a quantitative estimate of the possibility of that event occurring. If it is equal to zero, the event cannot happen in principle. When it is equal to one (100%), the event will necessarily occur.