blackjack - Card counting, Advanced strategy, Variants

A popular casino card game, derived from 15th-c European games. The object is to accumulate a score of 21 with at least two cards. Picture cards count as 10, the ace as either 1 or 11, and other cards according to their face value. A score of 21 with a picture card and an ace is called a blackjack. Multiple packs of cards are shuffled together and dealt face up from a mechanical ‘shoe’. The original bets are placed before the first card is dealt. Some cards are dealt face down in the casino game. There are several variations.

If both the player and the dealer have the same point value, it is called a "push", and neither player nor dealer wins the hand. Each player has an independent game with the dealer, so it is possible for the dealer to lose to one player, but still beat the other players in the same round. In European blackjack, the hole card is not actually dealt until the players all play their hands.) The cards are dealt face up from a shoe, or face down if it is a pitch game.

The play goes as follows:

If the dealer has blackjack and the player doesn't, the player automatically loses. dealer hits a soft seventeen (ace-six, which can play as seven or seventeen) European No-Hole-Card Rule: the dealer receives only one card, dealt face-up, and does not receive a second card (and thus does not check for blackjack) until players have acted. In Australia for example, a player beaten by a dealer blackjack may keep all split and double bets and lose only the original bet, thus the game plays the same as it would if there were a hole card.

Example: The player bets $10, the cards are dealt, the player's hand is 19, and the dealer shows an Ace. The player loses his $10 bet on his blackjack hand, but he wins the insurance bet, so the player gets 2:1 on his $5 Insurance wager and receives $10 (on top of the $5 which is returned to him). (If the player with the natural refuses the offer of "even money", and the dealer turns over his hole card to make a natural (a blackjack), it is a tie and the player's bet is returned to him.). For example in a seven player game, if no player is holding any ten card, it is actually correct to make the insurance bet, since the chance of the dealer drawing a ten card are increased significantly to pass the 2:1 odds paid.

In casinos where a hole card is dealt, a dealer who is showing a card with a value of Ace or 10 may slide the corner of his or her facedown card over a small mirror or electronic sensor on the tabletop in order to check whether he has a natural. This allows a player to potentially get many bets out in a situation that he is likely to win, such as against a dealer card of 6, the worst card the dealer can have. Note that even in cases where the casino shows both dealer cards face up, allowing the players to see the dealer's full hand, the rule is more detrimental to the player.

Basic strategy table

Your hand	Dealer's face-up card
	2	3	4	5	6	7	8	9	10	A
Hard totals
18-20	S	S	S	S	S	S	S	S	S	S
17	S	S	S	S	S	S	S	S	S	Rs
16	S	S	S	S	S	H	H	Rh	Rh	Rh
15	S	S	S	S	S	H	H	H	Rh	Rh
13-14	S	S	S	S	S	H	H	H	H	H
12	H	H	S	S	S	H	H	H	H	H
11	D	D	D	D	D	D	D	D	D	H
10	D	D	D	D	D	D	D	D	H	H
9	H	D	D	D	D	H	H	H	H	H
5-8	H	H	H	H	H	H	H	H	H	H
Soft totals
	2	3	4	5	6	7	8	9	10	A
A,9	S	S	S	S	S	S	S	S	S	S
A,8	S	S	S	S	D	S	S	S	S	S
A,7	D	D	D	D	D	S	S	H	H	H
A,6	H	D	D	D	D	H	H	H	H	H
A,4-5	H	H	D	D	D	H	H	H	H	H
A,2-3	H	H	H	D	D	H	H	H	H	H
Pairs
	2	3	4	5	6	7	8	9	10	A
A,A	SP	SP	SP	SP	SP	SP	SP	SP	SP	SP
10,10	S	S	S	S	S	S	S	S	S	S
9,9	SP	SP	SP	SP	SP	S	SP	SP	S	S
8,8	SP	SP	SP	SP	SP	SP	SP	SP	SP	Rsp
7,7	SP	SP	SP	SP	SP	SP	H	H	H	H
6,6	SP	SP	SP	SP	SP	H	H	H	H	H
5,5	D	D	D	D	D	D	D	D	H	H
4,4	H	H	H	SP	SP	H	H	H	H	H
2,2 3,3	SP	SP	SP	SP	SP	SP	H	H	H	H

The above is a basic strategy table for the most common 6- to 8-deck, Las Vegas Strip rules.

Card counting

Basic strategy provides the player with the optimal play for any blackjack situation, based on millions of hands played in the long run. By keeping track of the cards that have already been played, it is possible to know when the cards remaining in the deck are advantageous for the player.

There are several card counting systems which do not require that the player remembers which cards have been played. Rather, a point system is established for the cards, and then the player keeps track of a simple point count as the cards are played out from the dealer.

Advanced strategy

Because basic strategy is based on a player's point total, and the dealer's visible card, basic strategy plays can often be incorrect. A more complete strategy would require a much more complex table, which is why the table above is named 'basic.'

Advanced strategies take into account a player's hand composition (number of cards and their individual values). However if a player's total of 16 contains a 4 or a 5 card (such as a three card hand of 9 5 2), the correct strategy is actually to stand. Seeing which cards are currently out does not give a player enough information to make decisions based on deck composition, which requires card counting. Because of this, a cunning player may be able to play another player's double or splits by paying the bet himself, or even getting another player to pay to play one of the player's own split cards. In this situation a cunning player would offer to pay the bet and play one of the split hands, because 2 versus a 6 actually favors the player. If a player does this on a winning hand (any basic strategy double down hand is always a winning hand), a smart player can 'get in' on the double by offering to pay the rest of the double amount.

If a player prefers to hit instead of double (because he is worried about receiving a low card) in some rare situations it is actually correct to offer not only to pay the double, but to also pay the player back their bet should the hand lose. When a player doubles on 11 versus a dealer 6 they win over twice as often as they lose, so it is okay to lose the double bet and pay out the player his original bet. One such technique, mainly applicable in multi-deck games (aka shoes), involves tracking groups of cards (aka slugs, clumps, packs) during the play of the shoe, following them through the shuffle and then playing and betting accordingly when those cards come into play from the new shoe. This technique, which is admittedly much more difficult than straight card counting and requires excellent eyesight and powers of visual estimation, has the additional benefit of fooling the casino people who are monitoring the player's actions and the count, since the shuffle tracker could be, at times, betting and/or playing opposite to how a straightforward card counter would.

Other legal methods of gaining a player advantage at blackjack include a wide variety of techniques for gaining information about the dealer hole-card or the next card to be dealt.

Variants

Spanish 21 provides players with many liberal blackjack rules, such as doubling down any number of cards (with the option to 'rescue', or surrender only one wager to the house), payout bonuses for five or more card 21's, 6-7-8 21's, 7-7-7 21's, late surrender, and player blackjacks always winning and player 21's always winning, at the cost of having no 10 cards in the deck (though there are jacks, queens, and kings).

Another variant is Blackjack Switch, a version of blackjack in which a player is dealt two hands and is allowed to switch cards. For example, if the player is dealt 10-6 and 10-5, then the player can switch two cards to make hands of 10-10 and 6-5.