If card counting in blackjack is just keeping track of high cards vs low, does that mean if I could remember all the different cards used (i.e. how many 5s, how many 7s) I would be really good at blackjack?

Question

This would break online casinos because you could easily do that with electronics. Assuming the casino itself is playing fair.

If you could perfectly keep track of how many of which cards are left in the decks, and everytime make the most mathematically sound bet, would the house still have an edge?

(I assume the correct answer will start off saying I don’t understand how card counting works – fair enough, but what about the basic explanation of it did I misinterpret?)

In: Mathematics

Answer 1

Card counting works because unlike games like roulette, previous rounds affect future rounds. As cards get played out, they are removed from the game until the next shuffle. That means that if you are playing double deck blackjack and 6 aces are dealt in one hand, there are only 2 remaining until the next shuffle.

Card counters play perfect basic strategy and keep track of the ratio of high cards to low cards in the shoe. At certain points, the edge shifts in the players favor, and they increase their bets sometimes as much as 10x.

However, there are quite a few countermeasures casinos can take that make card counting completely ineffective such as having a 10 deck shoe and only playing through 5 decks. The count never gets high enough to give the player an advantage.

Online casinos can take it up a notch and shuffle after every hand for “free” because shuffling a virtual deck of cards is not very computationally expensive.

Brick and mortar casinos now have blackjack tables with auto shufflers or continuous shufflers that also mean any information about what cards have been played is useless and moves blackjack closer to a game of independent events instead of a game that has a state that can change.