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Modern Blackjack nth Edition

Dealer Upcard Manipulation

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There are times where the dealer might see the next card out of the shoe. Suppose that the dealer decides the upcard depending on this information? For example, if the dealer knows the next card is a ten, she will always make it the upcard and if it is not, will always make it the downcard. In this case, the house edge is a miserable 3.64%. (Miserable for the player.) Below is a chart displaying the house edge for the same scenario for each possible card, assuming six decks, S17, DAS, LS, and Basic Strategy:

The results are rather unusual looking, but make sense. If the dealer always turns up a ten and turns down all non-tens, the game is very bad because the player will bust more often and will not be able to split or double as often. The same scenario with an ace is good for the player, because if the dealer has an ace, it’s good to know about it. An ace hiding in the hole means the dealer is less likely to bust and can mess up the player.

One might expect that the overall results would average out to the normal house edge of .359%. But, in most cases, the player is hurt. This is because Basic Strategy is based on a set of rules, and this rule screws up all the Basic Strategy calculations. When we see a five up, we expect the hole card to have a specific chance of being each possible card. But, this manipulation changes all the probabilities, resulting in a poor player strategy.

So, if you see the dealer fail to always flip the same card – run.

Note: This is only one set of scenarios. The dealer could make more complex decisions based on the seen card that could be far worse.

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  1. realestate's Avatar
    hi i dont really get this post. i have read somewhere that if a dealer shows a T upcard, it is around a -18% for players, which is far from -3.64%. also what do you mean "fail to always flip the same card''?

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