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Table Games Blackjack odds question

Discussion in 'Table Games' started by mikeyvegas1, Jun 1, 2015.

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  1. mikeyvegas1

    mikeyvegas1 Low-Roller

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    Could some stats person help me understand. Its my understanding that the more decks the worse the odds can anybody tell me why that is? Also I have heard that the more people at a table the worse the odds is that true and if so why?
     
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  2. Brick

    Brick Low-Roller

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    I'm no math genius but it seems like the more decks in play, the better chance for the House/Dealer to get the card(s) they need to beat your hand. Less decks = better for player (but does not change the usual 43% player / 9% push / 48% House results from playing Basic Strategy). I don't think the number of players at the table matters. It just seems like it. Especially when someone makes a play that does not make sense under BS. Just my 2 cents.
     
  3. ngrund

    ngrund Low-Roller

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    the fewer decks, the better the chance of a blackjack so single deck is better than 4 or 6 decks, which is why the casinos began changing the payout on a blackjack from 3/2 to 6/5. the number of players matters for the same reason-better chance of getting a blackjack dealt to you.
     
  4. Snidely

    Snidely VIP Whale

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    Why the better chance of blackjack? The proportion of aces and paint doesn't change due to the number of decks.

    https://possiblywrong.wordpress.com/2012/03/11/why-fewer-decks-are-better-for-the-blackjack-player/

    This is an explanation I found online. Can't say I fully understand it.
     
  5. Brick

    Brick Low-Roller

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    The end of the article summarizes why fewer decks are better:

    "What else is there that varies with number of decks? The answer is: the probabilities of outcomes of the dealer’s hand. As mentioned at the outset, the probability of blackjack (which is the same for the player and the dealer) is greater with fewer decks. But more importantly, the probability that the dealer busts is also greater with fewer decks."

    Every card dealt changes the composition of the remaining deck(s) so more decks give the dealer (and player) more potential cards to pull from.

    Seems like following this train of thought inevitably leads one to consider counting cards...
     
  6. thefish2010

    thefish2010 Low-Roller

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    The number of people at the table makes no difference. You will also hear people saying things about "bad" players at the table affecting the odds or "making everyone lose". Overall, the strategy of any other player makes no difference (their "bad" play is statistically just as likely to help you as it is to hurt you). The edge increases with the number of decks for a number of reasons, the primary reason being that larger runs of smaller cards are possible. This means that the dealer will bust slightly less often as the number of decks increases.

    In general:

    1) Never play at a table where blackjack pays 6:5. Run away, fast.

    2) Never put a dime into action until you are aware of exactly what rules are in effect at the table (especially with regard to doubling after split and any doubling restrictions on your first two cards). At some casinos, two tables right next to each other in the same pit will have different rules.

    3) Never play at a table where you cannot double after split, unless it happens to be a 3:2 single deck game (which you are unlikely to find on the strip).

    4) Never play at a table that restricts you to doubling down on certain totals like 9,10, or 11.

    5) Try to find a game within your playing budget where the dealer must stand on soft 17. If you see "dealer must hit soft 17" on the felt, understand that you are going to lose approximately twice as fast as you otherwise would if they didn't hit soft 17. I only say try because you are unlikely to find these games below $25 on weekdays (even that is rare on the strip) and $100 on weekends. If you're playing $100/hand or over, there is no excuse to be playing with crappy rules.

    6) If you do not know basic strategy, buy a basic strategy card, and follow it to the letter regardless of any "feelings" you may have during a hand, or other players telling you things like "you're going to take the dealer's bust card!". They don't know the next card coming out anymore than you do, but there is a mathematically correct way to play each and every hand, and if you deviate from it, you will lose extra money. The correct basic strategy varies slightly with the number of decks you are playing and the specific rules of the game. You can find the wizard of odds basic strategy calculator here., and you can view the house edge if playing correct basic strategy for any given set of playing conditions here. You are allowed to use basic strategy cards at the table; if you feel like you cannot memorize the table for the specific game you're playing, print it from the wizard of odds page, cut it out, and put it in your pocket.
     
    Last edited: Jun 1, 2015
  7. mrem3200

    mrem3200 High-Roller

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    That's what I would have thought too. I am not sure I understand/agree with the post above that says differently...but it has been a long time since my last stats class so i may be wrong.
     
  8. mikeyvegas1

    mikeyvegas1 Low-Roller

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    Sons 21st birthday trip
  9. thefish2010

    thefish2010 Low-Roller

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    There are indeed some advantage plays that require additional players at the table - shuffle trackers have people to "eat" cards, for example, hoping to make sure that a slug of cards they've been tracking comes out when and on the specific hands that they want it to. That is the only time the number of players at the table would matter, but if you're reading this post, chances are you are not a shuffle tracker :) .

    Yes, a CSM is mathematically better for the player because you are essentially playing against a fresh shuffle every hand, instead of playing to a fixed point in the deck defined by the cut card. This is because when a large number of high cards come out in the beginning, play must continue until the cut card is reached, despite the existence of very few high cards - the cut card ensures that you'll play more hands at a higher disadvantage than you would if playing off the top of the deck every hand. But keep in mind the other important thing he said: "it must also be stressed that the CSM allows the dealer to deal continuously, increasing the number of hands dealt per hour. For the basic strategy player, this will result in a greater expected loss on an hourly basis.". Since CSM tables also tend to have worse rules than traditional tables, combined with an increase in the number of hands per hour, in most cases you will still lose more at a CSM - just not for the reasons that most players think they will.
     
    Last edited: Jun 1, 2015
  10. Hobofrank

    Hobofrank Prime Minister of Idiocracy

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    "but if you're reading this post, chances are you are not a shuffle tracker", you don't say?...
     
  11. topcard

    topcard Older than the Stardust!

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    The easiest way to understand the "fewer decks is better" notion is this way:

    Two deck...there are 32 10-value cards. In six deck, there are 3x as many - 96.

    Remove 20 little cards (2-6) from the two deck game, and your percentage of ten-value cards is 32/84...38%.
    Remove 20 little cards (2-6) from the six deck game, and your percentage of ten-value cards is 96/292...33%.

    The higher percentage of ten-value cards remaining in the deck is better for the player.
     
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  12. nostresshere

    nostresshere Mr. Anti Debit Card

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    Lots of fancy math involved, but do some simple logic.

    While playing BJ, the next card is going to 1 of 52 possible cards. (or 104 or 156, etc.). That next card could care less how many players, or if the good card goes to dealer or to player, or if the last player did something stupid or smart. It is just another card. There is no way around that. It is still just another card.

    If you are a counter or vaguely aware of the deck dealt so far, then some skill might change your betting. If you can not counting or following the deck, it does not matter.

    But it is just another card. There is no way around it.

    Some folks like to say a constant shuffle changes the odds. Partly true. It does NOT change the odds of the current hand. But, since it allows for MORE hands to be dealt in the same time, the house therefore has more chances to get their edge from you.
     
  13. nostresshere

    nostresshere Mr. Anti Debit Card

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    The above assumes some sort of counting/tracking. Nothing else changes if a 1 deck or 20 deck. Nobody is adding or removing "little cards" at a faster or slower rate compared to overall mix of cards.
     
  14. topcard

    topcard Older than the Stardust!

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    Now, you can flip this (to a point).
    Remove 8 ten-value cards from the two deck game - you have 24/96 - 25% left.
    Remove 8 ten-value cards from the six deck game - you have 88/304 - 29% left.

    The reason fewer decks is still better even in this situation is that you have a greater house-advantage situation with both games...the two deck game will be re-shuffled after 4 or 5 hands. The 6-deck game? Try 25 hands or so. In a negative situation, the two deck game resets MUCH faster than the 6-deck game.
     
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  15. topcard

    topcard Older than the Stardust!

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    Has to do with the number of hands and the mix of cards remaining. In any circumstance (positive or negative for the player) the number of hands dealt in a 6-deck game is going to assure that more "small cards" will be in play than in a two deck game (prior to the shuffle).
    That will always be a greater house edge.
    It has to do with the ratio of smaller cards to larger ones.
    Pull x amount from a two deck game - that will always pose a greater ratio difference than with a 6-deck game.
    The difference (for positive or negative) is that the two deck game will be reset far more quickly... About 4-decks are in play for a 6-deck game & roughly 1 deck is in play for a 2-deck game. 52 cards cut away on the 2-deck game...104 cards cut away on the 6-deck game.
    Sure, one can get lucky and stumble into a very ten-rich 6-deck shoe. It's even happened to me a few times.
    What has happened FAR more often is a neutral or negative 6-deck shoe that lasts for 25 or 30 hands before a shuffle.

    EDIT - I get what you're saying, and that would apply to a CSM. The number of decks in a CSM is not relevant. They ALL go right back into play. So, the ratios always remain equal.

    EDIT #2 - PS: I will always prefer a CSM to a six-deck shoe for that very reason. Never a 'negative' shoe...no counting necessary.

    You say nobody is removing little or large cards at a different rate...but reality begs to differ. Unless a deck/shoe is perfectly balanced, there will always be an imbalance between tens & small cards.
    That imbalance last longer on a 6-deck game. Sometimes that works to your favor. Far more often, it does not.
     
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  16. thefish2010

    thefish2010 Low-Roller

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    For the record, this is not mathematically accurate. See here.

    1 deck, H17, DAS, DOA, 3:2, edge on CSM is 0.04645%

    6 deck, same rules, is 0.61873% - that's an increase in edge of over 13X vs single deck.
     
    Last edited: Jun 1, 2015
  17. ngrund

    ngrund Low-Roller

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    as far as the number of decks making the odds of a blackjack better, and to keep it simple:

    take as a given that the first card drawn is an ace
    with one deck the odds of the second card being a 10 or face is 4/51=.07843137255
    with four decks 4/207=.0193236715
    six decks 4/311=.01286173633
    eight decks 4/415=.00963855422
     
  18. nostresshere

    nostresshere Mr. Anti Debit Card

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    Why does it change? Why is this different?


    And, even if this is totally correct, the house edge in your example goes for 4/100ths of a percent to 6/10ths of a percent. Not exactly a major variance anyways.
     
  19. Riders

    Riders High-Roller

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    I think I am missing something.

    If an ace is drawn then the odds that a 10 or face card is 16/51 with a single deck. With 4 decks it is 64/207 ... and so on. I didn't do the math but those seem alot closer than the above.

    But then again what do I know, I play LIR.
     
  20. ngrund

    ngrund Low-Roller

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    I was very tired last night when posting that s/b
    16/51=.3137254902
    64/207=.30917874396
    96/311=.30868167203
    128/415=.30843373494

    this is very simplified as it is taken as a given that first card is an ace.
     
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