The strategies for winning blackjack

by Yinan Wan, Rapidamic Lab

Rapidamic Lab
4 min readOct 5, 2021

Card game is, literally, games using cards, but there are also many categories of it. Board games, poker cards, TCGs (trading card games), and online games are all included in it. The common point is that in these games, there is always a “deck” containing cards in unknown sequence. We know what cards are in the deck, but we will never know which card is on the top of the deck. However, we can still categorize the cards, calculate the odds, and make decisions according to these results. These strategies will help players “play better.”

Blackjack is one typical example of card games. It is a popular but simple game played with poker cards. In this game, there are one dealer and several players. For all cards, “A”stands for 1 or 11, 2–10 stand for their own value, and “J”, “Q”, “K” stand for 10. The dealer initially has 1 face-up card and 1 face-down card. Then each player starts with two cards. They may choose to hit (get an additional card randomly from the deck) until they stand (choose to stop hitting) or exceed 21, which is called “bust”. The player who busts loses the game immediately. After the players all finish their turn, the dealer will hit until he reaches 17, and if he does not bust, the players with greater total value win, and the players with smaller total value lose.

This is the basic rule of blackjack. Also, many people tried to research into it. In general, researchers focus on its strategies. For example, some people tried to find some good strategies of blackjack.[1] Obviously, each time when the player “hit”, the total value must increase, but the risk of bust stops him from hitting infinitely. However, if the player does not hit, maybe his total value will be lower than the dealer, thus lose the game. In this situation, if the player knows the value of the next card, the answer will be very clear: hit if it will not bust. Unfortunately, this is a card game, and we can never know exactly the value of it. Then, probability should be used here to help solve this problem. The result will be much more simple, like, “hit when having a hand of A+6”.

Moreover, there is another widely used strategy in card games: counting cards. Like it is said in the beginning of the article, we know what cards are in the deck. However, as we play the game and draw cards from the deck, the remaining cards are changing. For example, if I have a “J” and a “K” in my hand, I know that there is 1 less “J” and 1 less “K” in the deck. It sounds simple and meaningless, right? No. In another situation, I have 4 “2”s in my hand. If I’m playing with only one set of playing cards, there will be no more 2 in the deck. In this situation, card counting affects decision making greatly. An article specifically talks about how this strategy affects the odds of winning.[2]

After that, since blackjack is a popular casino game, how can dealers earn money by this game? There is a terminology called “house edge”, which means the advantage of the casino in this game. In average, or in the long run, the players will lose money due to the house edge. For blackjack, the house edge is very small if the players can play very well. It is possible for players to earn money from the casino if they can effectively use strategies including the two I just introduced. On the other hand, if players have poor decision making skills, the house edge of blackjack can be as much as slot machines.[3] It is a very appropriate metaphor since they are almost “randomly” draw cards from the deck.

For card games in general, since there is not always a “casino” earning money, game designers need to make sure that every player has an equal gain, or in some situations, an equal opportunity of winning. This can be solved simply by making all the players equal, but it is not a good solution because it will be a boring game. Therefore, game designers need to use other tools, like probability, to make the game with different players more fair. In the blackjack game, there are dealers and players. If we can design a “fair” blackjack game, it may help us design other “unequal” fair games or make other games more fair.

Reference

[1]Zhao, Mu. “Continuous Blackjack: Equilibrium, Deviation and Adaptive Strategy.” arXiv preprint arXiv:2011.10315 (2020).

[2]Vidámi, Mózes, László Szilágyi, and David Iclanzan. “Real Valued Card Counting Strategies for the Game of Blackjack.” International Conference on Neural Information Processing. Springer, Cham, 2020.

[3] from https://www.youtube.com/watch?v=PljDuynF-j0

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