The probability of an event is usually described as the chances for the event to occur over the total chances for the event to occur (chances for / total chances). In the case of a deck of 52 cards, the probability of drawing a king from the deck is 4/52 = 1/13 = 0.077, or 7.7 percent. As seen above, the odds, or the ratio of chances for to chances against (chances for : chances against) can be found by the formula: total chances equals the chances for plus chances against (or total chances = chances for + chances against, or chances against = total chances - chances for). Thus, the odds of picking a king from a deck of 52 cards is 4:(52 - 4) = 4:48 = 1:12.