Knowing the approximate content of the deck allows the player to build an appropriate strategy. Basic strategy says to hit a 16, when the dealers up-card is a 10. In this case hitting gives higher odds to the player, but the difference is small, and if the deck is rich in 10-count cards, that alters the odds in favor of standing. However, this is not the main advantage of blackjack card counting. Above all, card counting permits the player to calculate his odds and to bet larger amounts when the deck is favorable to the player and smaller amounts when it is not. In the long run, the deck is more likely to be unfavorable, but following the card counting system precisely can still be profitable to the player.
It is difficult to remember all cards that have been dealt, especially when the game is player with multiple decks. Therefore, card counting schemes assign a point value to each card and sum it to the running tally. Each specific card counting method has its own scheme of points, but usually, low value cards, as 2, 3 or 4 are assigned a positive value, and 10-count cards are given a negative one. The running tally itself does not represent the number of good and bad cards in the deck. It must be divided to the total number of the cards left in the deck. Only unbalanced count methods do not require this adjustment, because that is already factored into the count.
Professional counters have an expectation of 1-1.6 percent gain, while their yearly income may reach low six figures US dollars, which is comparable with other mental field professions. Other counters may use card counting to make the vacation pay for itself or just to have some fun. However, card counting does not guarantee fantastic wealth and is quite difficult to perform. The player must keep carrying out his calculations very accurately, despite all possible destructions. A small miscount can ruin the whole process. In fact, not many card counting attempts succeed. Most fail because of errors made by the player. Besides, the counter must act the way the casino will not notice that any counting is taking place. Although card counting is not illegal, casinos have their own countermeasures to avoid losing money. If a casino notices a counter, it will first check to see if the counter is good enough to worry about, and ignore him otherwise.
Level one counts assign 1, 0 and plus 1 values to all cards. Level one counts are easier to perform, but provide low calculation accuracy. More precise counts assign different values for different cards. These methods are called multi-level counts and are much more difficult to perform. Although multi-level counts are more accurate, sometimes it is advisable to sacrifice the accuracy of the count itself to reduce the number of errors.
Another big question in card counting is how to treat aces. Normally, aces are a bit disadvantageous for the player, but they can form a blackjack, and in this concern they are extremely valuable. Many schemes give aces a negative value, recognizing that there is a compromise involved. More sophisticated schemes assign zeros to aces in the global count and require keeping a separate count for aces. It surely is a more appropriate way to treat aces, but it complicates the process even more.
Card counting was invented by American mathematician Edward O. Thorp in 1962. He also published the first counting scheme in his book Beat the Dealer, which has become a classic in gambling literature. However, this book is no longer up-to-date. Casinos have changed many rules and procedures in response to growing population of card counting methods. End play, for example, no longer exists, because casinos do not deal to the last card. Also, the 10-count system described in the book is less profitable and harder to use than other systems developed later.
Hi-Lo is a level one scheme most commonly used by professional counters. Another effective counting scheme is K-O, an unbalanced system developed by Ken Fuchs and Olaf Vancura, where 7s also receive plus 1 value. K-O is a little less effective than Hi-Lo, but it is much less error-prone.