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Thread: ISO Mental shortcuts for dividing by fractions

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    ISO Mental shortcuts for dividing by fractions

    I'm hoping that there exists a set of shortcuts for calculating TC when remaining decks is an inconvenient number like 2.25 or 3.5. It takes me too long to mentally divide, say, 17 by 4.5 - quick is it 3 or 4?

    For example, with 1.5 decks remaining, I find it easier to double the RC and then divide by 3. Is there a set of similar tricks to deal with other divisors?

  2. #2


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    I don't start dividing by halfs until I get past 3 decks in a 6D shoe. If you want to Divide by 2.5, then simply multiply your RC by 4, then move the decimal.

    Example/ If your running count is +15 and you have 2.5 decks left to play; multiply 15x4 = 60. Move the decimal over, so 60 = 6.0 now. Your TC = +6.

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    Yes, that's exactly the type of thing I'm looking for. I'm sure I could invent some myself, but figured others had already done so. Thanks!

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    Quote Originally Posted by Optimus Prime View Post
    It takes me too long to mentally divide, say, 17 by 4.5 - quick is it 3 or 4?
    The multiples of 9 you learned by rote as a group in elementary school are the even multiples of 4.5. Assuming flooring that is all you need to know to get the answer instantaneously without using math. The second multiple of 9 is 18 (also the second even multiple of 4.5 which is the TC +4 RC barrier). Since the RC of +17 is closer to 18 (The second even increment of 4.5 or TC +4) than 9 (The first even increment of 4.5 or TC +2) and in between them, so the TC is floored to TC +3. You do this for a while and you know the TC instantaneously every time without even thinking about it. No math since you learned the multiplication tables by learning all the multiples of each number as a group. Your brain already has the increments in your head. You just need to use the increments as a mental ruler. For half decks you use double the deck estimate to get the even TC increments as I demonstrated here. Doing it this way you have instantaneous TC recognition without doing any math. You just put the RC to the mental ruler that was engrained into your memory when you first learned to multiply numbers. instant TC recognition.

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    Quote Originally Posted by Three View Post
    The multiples of 9 you learned by rote as a group in elementary school are the even multiples of 4.5. Assuming flooring that is all you need to know to get the answer instantaneously without using math. The second multiple of 9 is 18 (also the second even multiple of 4.5 which is the TC +4 RC barrier). Since the RC of +17 is closer to 18 (The second even increment of 4.5 or TC +4) than 9 (The first even increment of 4.5 or TC +2) and in between them, so the TC is floored to TC +3. You do this for a while and you know the TC instantaneously every time without even thinking about it. No math since you learned the multiplication tables by learning all the multiples of each number as a group. Your brain already has the increments in your head. You just need to use the increments as a mental ruler. For half decks you use double the deck estimate to get the even TC increments as I demonstrated here. Doing it this way you have instantaneous TC recognition without doing any math. You just put the RC to the mental ruler that was engrained into your memory when you first learned to multiply numbers. instant TC recognition.
    +1

    Exactly what I was gonna say but was too tired to type it out

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    Quote Originally Posted by Ryemo View Post
    ..Example/ If your running count is +15 and you have 2.5 decks left to play; multiply 15x4 = 60. Move the decimal over, so 60 = 6.0 now. Your TC = +6.
    Seriously?... that's 5+ (5 plus)...bet/play as 5/6 depending on situation/risk tolerance/br/heat/etc....no need to complicate it imo

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    Quote Originally Posted by Optimus Prime View Post
    I'm hoping that there exists a set of shortcuts for calculating TC when remaining decks is an inconvenient number like 2.25 or 3.5. It takes me too long to mentally divide, say, 17 by 4.5 - quick is it 3 or 4?

    For example, with 1.5 decks remaining, I find it easier to double the RC and then divide by 3. Is there a set of similar tricks to deal with other divisors?
    Not a multi-year pro yet, but nonetheless I find that it's much easier to conservatively "estimate" by truncating.

    Taking a subset of your example: 1.5 decks in shoe, assuming 6 deck game means 4.5 decks in discard tray (DIT) ((of course, this does not account for any cards shown on the table)). I view the DIT and I know that it's somewhere between 4 and 5, so I conservatively round DOWN to 4 DIT (meaning (conservatively) there's 2 decks left in shoe); and then divide the running count 17 / 2 (a much easier division) is TC=8.5, or 8.0 to be even more conservative.

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    Quote Originally Posted by Sharky View Post
    Seriously?... that's 5+ (5 plus)...bet/play as 5/6 depending on situation/risk tolerance/br/heat/etc....no need to complicate it imo
    Huh? What are you talking about?

    1) I hope you understand that I was simply outlining an example to demonstrate how the math works out to quickly divide any given number by 2.5. I could have used any number, so I chose +15.

    2) Not every person with a TC of +6 automatically means max bets. I use Zen Count, so my +6 is roughly equivalent to a +4 Hi Lo. So your logic would not apply to me or anyone else using a level 2/3 count.

    The OP asked for a simple “trick” that could be used to quickly divide the running count by numbers such as 2.5 quickly in your head; that’s what I provided.
    Last edited by Ryemo; 10-15-2018 at 07:26 PM.

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    Quote Originally Posted by Ryemo View Post
    ....I use Zen Count, so my +6 is roughly equivalent to a +4 Hi Lo. So your logic would not apply to me or anyone else using a level 2/3 count....
    both irrelevant...no need to over complicate converting rc to tc...you should know if it's either "high", or "low" on your whole #

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    Quote Originally Posted by Sharky View Post
    both irrelevant...no need to over complicate converting rc to tc...you should know if it's either "high", or "low" on your whole #
    There is nothing complicated about multiplying your RC by 4, then shifting the decimal IMO. But that isn’t what we’re talking about.

    If you want to divide your RC by whole numbers, then fine. But if you want a little bit more accuracy (as the OP stated), then this is one way of doing it.

    So again, I have no idea what your point is. The original poster asked the board for a simple trick he/she could use to convert the running count into a true count quickly in his/her head. That is exactly what I provided.

    Do you disagree?

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    Quote Originally Posted by Ryemo View Post
    Huh? ..Not every person with a TC of +6 automatically means max bets. ..
    not sure what this has to do with ANYTHING???

    Quote Originally Posted by Ryemo View Post
    Huh? ....I use Zen Count, so my +6 is roughly equivalent to a +4 Hi Lo.j....
    great...my suggestion here is to learn, calculate (Norm's software?) to calculate the indices for the count you imply

    Quote Originally Posted by Ryemo View Post
    Huh? .... So your logic would not apply to me or anyone else using a level 2/3 count. ...
    makes NO sense, either...those using level 1 counts also have to deal w/ fractions...

    GOOD LUCK!!!!!

  12. #12


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    Ok Sharky... let's recap:

    Optimus Prime starts thread like this:

    Quote Originally Posted by Optimus Prime View Post
    I'm hoping that there exists a set of shortcuts for calculating TC when remaining decks is aninconvenient number like 2.25 or 3.5. It takes me too long to mentally divide,say, 17 by 4.5 - quick is it 3 or 4?


    My response was this:

    Quote Originally Posted by Ryemo View Post
    I don't start dividing by halfs until I get past 3 decks in a 6D shoe. If you want to Divide by 2.5, then simply multiply your RC by 4, then move the decimal.

    Example/ If your running count is +15 and you have 2.5 decks left to play; multiply 15x4 = 60. Move the decimal over, so 60 = 6.0 now. Your TC = +6.
    Optimus Prime responds with:

    Quote Originally Posted by Optimus Prime View Post
    Yes, that's exactly the type of thing I'm looking for. ... Thanks!
    This is where that part of the conversation should have ended IMO, but...

    Quote Originally Posted by Sharky View Post
    Seriously?... that's 5+ (5 plus)...bet/play as 5/6 depending on situation/risk tolerance/br/heat/etc....no need to complicate it imo
    uh... WTF? lol

    The guy wanted more accuracy. If he wanted to just round to the nearest number, then he wouldn't have asked the question he did.


    Last edited by Ryemo; 10-16-2018 at 03:37 PM.

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    And in response to your last post... I assumed you meant that because the count was +5 or greater, that's typically when most people who use Hi Lo max out and there aren't many other indices to utilize once you get past that point. That's what I assumed you meant. So my rebuttal to that point was that many people who use higher level counts do not "cap out" at +5 or +6... That was my point!

    After re-reading your post, I'm guess you meant that once you get to this point ("5 plus"), just utilize any indices that would fall in the +5 or +6 category. And that's fine if you want to do that. But the OP was not seeking that.
    Last edited by Ryemo; 10-16-2018 at 03:48 PM.

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