"A common special case occurs when all outcomes are equally likely. This usually happens when we roll dice, flip coins, or deal cards, since the probability of rolling a 3 is normally the same as rolling a 6, and the probability of being dealt the 10♠ is the same as the Q♦. It may also happen when we generate encryption keys, choose between alternate network routing paths, or determine the initial positions of enemies in a first-person shooter level. If there are N possible outcomes, where N = |Ω|, then the probability of any event A is Pr(A) = |A|/N. It is the size, or cardinality, of the event set that matters, and the ratio of this number to the total number of outcomes is the probability. For example, when dealing a card from a fair deck, the probability of drawing a face card is Pr(F) = |F|/N = 12/52 = .231. This shortcut only applies when the probability of each outcome is the same. We could not say that the probability of a user’s password starting with the letter q is 1/26, because passwords surely do not contain all letters with equal frequency. The only way to solve a problem like this is to know how often each letter of the alphabet occurs."