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Thread: Deck estimation, would you dvide by 2 or 1.5?

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    Question Deck estimation, would you dvide by 2 or 1.5?

    Steps to calculate the True Count:

    1. Obtain the RC through card counting.
    2. Eyeball the discard tray, minus the cut card, plus the seen cards on the table to estimate the remaining deck.
    3. Round up the remaining deck estimation to the nearest half deck.
    4. Divide the RC by the remaining half deck to get the TC estimation.
    5. Floor the TC estimation to the nearest integer.

    I'm talking about step 3 here.
    From a lot of sources I've gone through, all of them suggest rounding up rather than rounding or flooring.
    Thus, I always round up my remaining deck. For example, 2.2 decks remaining, I divide by 2.5; 3.7 decks remaining, I divide by 4.
    However, in some cases near the end of a shoe, I just feel it's incorrect to round up.

    For example, in a 6 deck game, after a round of play, there are no cards on the table.
    From eyeballing, I can tell there are 4.4 decks in the discard tray, so there are 1.6 decks remaining.
    Since 1.6 decks round up to 2 decks, I would divide by 2 decks, but round down to 1.5 decks provide a more accurate TC.
    9/1.6=5.625 Exact
    9/2=4.5 Round up
    9/1.5=6 Round down

    To rephrase my question, should I round down if I can clearly tell that round down gives me a much closer TC estimation?
    For example:
    1.1 deck round down to 1, rather than round up to 1.5.
    0.6 deck round down to 0.5, rather than round up to 1.

  2. #2


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    Learn to your interpolate - much simpler, more accurate.

  3. #3


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    Do the division by remaining decks as accurately as you possibly can, with no rounding at all. Then floor the result.

    Don

  4. #4


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    I just figured you should round as close as possible, and if you're right in the middle, at a quarter deck, you should be able to calculate TC for each surrounding half deck quickly.

    Example: RC 17, decks remaining 2.25.

    So I should know almost automatically, if 2.5 decks left, TC 6.5. If 2 decks left, TC 8.5. So meeting in the middle at 7.5 should be a decent estimate.

    And turns out 7.5 is precisely correct.

    Since TC conversions with half decks remaining should be automatic, I find this way easier than dividing to a quarter deck

    Otherwise I'd figure just be conservative if in a crunch and round for a slightly lower count as you suggested, rather than a slightly higher one.
    Last edited by CountinCanadian; 09-28-2018 at 09:03 PM.

  5. #5


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    Quote Originally Posted by DSchles View Post
    Do the division by remaining decks as accurately as you possibly can, with no rounding at all. Then floor the result.

    Don
    Depending on perspective, I both agree and disagree. If you can’t calculate on the fly that portion of cards remaining beyond a full deck, then flooring as you described is the way to go. If you have the ability to interpolate, or described a different way, of being able to calculate half true counts, then flooring to the nearest half true count is the way to go.

    For the benefit of others, when simming scenarios on cvcx, there is an optional radio button that allows calculation of optimal betting by half true counts. There is a slight difference in optimal betting when flooring to full true counts versus half true counts.

    Curious of course, to your thoughts on the matter.

  6. #6


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    Quote Originally Posted by CountinCanadian View Post
    I just figured you should round as close as possible, and if you're right in the middle, at a quarter deck, you should be able to calculate TC for each surrounding half deck quickly.

    Example: RC 17, decks remaining 2.25.

    So I should know almost automatically, if 2.5 decks left, TC 6.5. If 2 decks left, TC 8.5. So meeting in the middle at 7.5 should be a decent estimate.

    And turns out 7.5 is precisely correct.

    Since TC conversions with half decks remaining should be automatic, I find this way easier than dividing to a quarter deck

    Otherwise I'd figure just be conservative if in a crunch and round for a slightly lower count as you suggested, rather than a slightly higher one.
    You are learning, grasshopper.

    https://youtu.be/U11bGxlmnVk
    Last edited by Freightman; 09-28-2018 at 09:08 PM.

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    My personal opinion is you are trying to be too precise. Why are you worrying about the one cut card in the discard tray. I also wouldn't try to get so accurate that I'm using half decks except maybe for the last playable deck of the shoe.

    Here is how I would do it for a six deck game. I would look at the discard try and round to what I see is the closest deck. If I see 2.3 decks in the discard try I would call it 2 and subtract 2 from 6 and divide by 4.

    If playing a two deck game I would multiply instead of divide to get true count. Think .5, .6, .7, .8. and for the shitty games I play the game is pretty much over by then.
    Exact ..... Use
    0.1667___ .2___6 decks left
    0.2000___ .2___5 decks left
    0.2500___ .3___4 decks left
    0.3333___ .3___3 decks left
    0.5000___ .5___2 decks left
    0.5714___ .6___1.75 decks left
    0.6667___ .7___1.50 decks left
    0.8000___ .8___1.25 decks left
    1.0000___ 1___ 1 decks left
    1.3333___ 1.3__.75 decks left
    2.0000___ 2___ .50 decks left
    3.0003___ 3___ .33 decks left
    4.0000___ 4___ .25 decks left
    Last edited by Midwest Player; 09-28-2018 at 09:39 PM.

  8. #8


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    Actually, I don't intend to make things more complicated, so I would always divide by half deck.(not quarter deck or even smaller fraction)

    If exact 1.7 deck remaining, and I only have two options:
    1. Always divide by 2 deck
    2. Always divide by 1.5 deck
    which option generates more risk adjusted EV over the long run?

    ???? PACM00 ?? Tapatalk??

  9. #9
    Senior Member Bubbles's Avatar
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    From eyeballing, I can tell there are 4.4 decks in the discard tray, so there are 1.6 decks remaining.

    Since 1.6 decks round up to 2 decks, I would divide by 2 decks, but round down to 1.5 decks provide a more accurate TC.
    For one, my eye balling isn't that good. At 4.4 decks in the discard try, I probably see it as 4.5 decks.

    Mentally I come to my TC like this:
    I note the RC /1 decks
    The RC /2 decks
    Then think of a number about half way between them. This is my TC.

    If I see 4.25 decks, I adjust aces based on 4.25, then divide by 2 for my TC. Sometimes I'll remember to +1 to the TC if my running count is odd.

    If I see 4.75 decks in the discard tray, I adjust aces by 4.75. RC basically equals TC, but not all the way. I just lower my RC by a smidge.

    I suck at mental math. This is how I do it. I don't always come to the correct TC, but it's close enough for me. The proper way would be to drill or find simple ways to come to the correct TC.


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    Last edited by Bubbles; 09-29-2018 at 02:16 PM.

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    I prefer to err on the conservative side. The important thing is to do what your sim you base bets and plays on does it. You are describing making playing decisions when you say including all the cards seen on the table. Griffin said you can lose most of your index play gain if you systematically apply the deviation too early. By dividing by a smaller number than decks remaining you would be causing what Griffin warned against to happen. But for betting decisions at deep pen floating advantage starts to kick in. In this case the error of dividing by a smaller number of decks remaining can help factor in that floating advantage.

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    i use what Colin suggested . i divide by whole deck the first 4 decks with some interpolation as freightman does , then i basically memorized a bunch of RC to TC that is after 4.5/6 until the end . of course if there are 90% plus pen then i need to be as accurate as i can . near the end it is just rc plus 10 % , 20 % , 30 % ... etc.. Or you can do what rick blaine does (i read it somewhere) He is accurate down to every card for deck estimation . G L with that .

  12. #12


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    Quote Originally Posted by Three View Post
    In this case the error of dividing by a smaller number of decks remaining can help factor in that floating advantage.
    Disagree as to form. I think it far more effective to calculate decks remaining as accurately as possible. Then, factor in an additional .25 to approaching .5 at 5.0/6.

  13. #13


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    I find that multipliers work very well for DD games. Midwest player listed some good values. I work my way up from .5--.6--.7--.8 etc from the top of the shoe. One common newbie folly is to not keeping mind that as you get very deep into DD games well into the last deck, very low RC will have a large TC max bets. I do believe quarter deck accuracy is well worth it in DD and the multiple method is a good way to achieve it.

    On 6D I worry less about the accurate TC early in the shoe. I simply keep the RC and as I enter into extreme positive or negative territory I will actively start calculating TC every hand. I think its a waste to worry about it when you are early in the shoe and the RC floats around the 0 point most of the time. Keep in mind that a good portion of 6D games are not what i would consider "deep" cut, with most of them ending well before the very accurate deck. estimation requirements start to really benefit. Multipliers work well for 6D as well IMO. Everyone will have a method that works best for them. If you are accurately estimate half decks in shoes then you are more than fine. Even just one deck accuracy is going to be more than plenty in most situations.

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