Data Science

Blackjack Crash Course: How To Count Cards

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Who didn’t want to be the smart genius kid from movies like „21“, making a fortune by fooling casinos with his math skills? ♠️ 💰

Today we will show you how to win big when it comes to Blackjack!

Blackjack is a classic card game that for many years has seen gamblers across the world come to the card table trying to win big. Whether it’s in films like Ocean’s Eleven, Rainman, or 21, the suave and sophisticated come to the casino to try to stake their claims and win the money.

Like any card game, there’s always risk involved, as you never quite know which cards will come up – but there are ways you can mitigate the risk.

You just need to be good with numbers. It’s not about being a math genius, but about having a knowledge of patterns and rules that help you get under the skin of the game and give you an advantage. The house might always seem to have an edge – but it’s actually the numbers that rule.

And in this article, we’re going to show you how to work those numbers. 


So How Is Blackjack Played?

♠️  Unlike most card games, Blackjack is played against the dealer, not other players. That’s the first thing that’s a bit different.

♥️  At the start, the dealer deals two cards to each player and themselves.

♣️  All of the cards are revealed – turned face up – other than one of the dealer’s cards. Simply, each card is worth the number value attached to it — 2 is worth 2, 3 is worth 3, 4 is worth 4, etc., and face cards (Jack, Queen, King) are worth 10.

♦️  Aces can be worth either 1 or 11 and the dealer announces whether Aces are high – worth 11, or low – only worth 1.

♠️  Each player looks at their cards and has the option to ‘hit’ – which means going for another card, or ‘standing’, which means sticking with what they have.

♥️  The aim is for the sum of the cards to be as close to 21 as possible, but never going over, as that means you go ‘bust.’

♣️  The winner is the person who is closest to 21 – so a 10 and a 9 would win against a Jack and a 6, for example.


The House Edge

The one big edge the casino has is that players can bust and lose before the dealer even plays their hand.

The house edge is a term used to show the mathematical advantage the casino has over the players.

Blackjack is unique in this way, as players are not combating a fixed house edge. In roulette, for example, the casino’s advantage remains a constant no matter what you bet on, but in Blackjack, the house edge varies throughout the course of the game.

Having said that, casinos assume a 2% edge over the aggregate of players that play Blackjack. This means that the house stands to win, on average, 2% of all the money that a player places on their wager. And when bets are high, that can be an awful lot of money.


How Math Can Help

Blackjack games are played with a finite set of cards – one or many decks. By remembering which cards have already been dealt, it’s possible to calculate which cards are still to come, by keeping a mental log of what has already been played.

You can also predict the actions of the dealer. They will always hit anything below 17. Knowing this means that it’s possible to build a system that ascribes a value to cards as either ‘good’ or ‘bad.’

There are certain ‘good’ cards (high cards, such as Aces and face cards) and certain ‘bad’ cards that you don’t want dealt (low cards, such as 6s). This is how a strategy is constructed using conditional probability.

There are two things you need to know:

♦️  The player should bet higher if more bad cards have been removed – which means more good cards remain.

♠️  Bet lower if more good cards have been played already as that means more bad cards remain.

Bad cards – bet high. Good cards – bet low. This is the basis of how card counting works…


Crash Course On The Hi-Lo System

The Hi-Lo system was first introduced in 1963 by Harvey Dubner, and has been used by a number of Blackjack experts. It’s a strategy of card counting based on simple addition and is used to determine whether a high or low card is likely to come next. This mathematical theory is based on the sum of the cards that have passed, and gives us a clue as to which cards are left in the deck.

In the Hi-Lo card-counting system, each card has one of the three following points: -1, 0, and 1: It’s simple – cards numbered 2–6 are worth +1, cards numbered 7–9 are worth 0, and 10s, face cards, and Aces are worth -1. What you need to do is ‘keep the count’ by adding up all of the cards that have been dealt using the point system detailed.

The larger the sum becomes, the more large cards remain in the deck. If the count is negative then the player knows that many of the Aces or cards valued at 10 have already been dealt, meaning many cards with smaller values remain in the deck.

Generally speaking, the player should bet heavily if the count is higher, but the lower the ‘count,’ the better the odds for the dealer, so the player should bet lightly or not at all.

For example, if a 10, 7, 3, & Q have been dealt, the points value (or ‘the count’) would be (-1)+(0)+(+1)+(-1) = -1 – which means you should bet low. If the running count increases, the advantage shifts to the player, but when the running count goes negative, the casino’s advantage increases.

And this is not what we want to hear. We’re the better player, and we want to win.

Think it sounds easy? It is a simple process. Maybe deceptively so. The Hi-Lo system works because it’s based on pure probability. However, to say it’s easy would be to overlook two points of complexity:

♥️  Blackjack is played with likely up to six decks

♣️  Blackjack is almost never two-handed (only player vs. dealer)

Once you start playing with a few people, it doesn’t matter how simple the math is – it’s all about speed and precision. You can be a math genius, but you also need to be smart, speedy, and have a brilliant memory. Card counting involves simple addition and subtraction, a great memory, and a clear head under pressure.

Have you got what it takes?


Want To Be Smarter Than Others?

Why not be smarter also with your business and leverage math and numbers to increase your investment returns or multiply your revenue?

RetentionX is an out-of-the-box solution that uses AI-driven data analysis. CEOs and companies that use RetentionX also gain an advantage, just like with card counting in Blackjack. It’s all about using maths and predict future outcomes to gain an advantage over those not making use of the technique.

 

Sources:
Jesus Najera, „How To Count Cards“

Data Science Enthusiast, growing revenues with the power of data – Founder & CEO of RetentionX, the leading Software for Decision Intelligence.

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