I need help with this play

2 decks dealt face up, table min: 5, max: 500

5 people remaining and 2 will advance to the next round. This is the last hand, I am the table chip leader (small lead) and bet last. All players including me push out a max bet, so if the whole table win or lose, I would advance. One player was dealt a BlackJack which pays 2 to 1, so he advances for certain. I was dealt a 12, other remaining 3 players were dealt hands of 17, 18, and 19 and the dealer showed a face card. What happened was that I hit my 12 and busted and the dealer turned up a 5 under, he hit a 10 and busted.

So my question is mathematically, which choice is bettter: hitting hard 12 to make at least 17 or better or stand on my hard 12, hopping the dealer has 20 or bust? I think that hitting is still a better choice, considering that the dealer is more likely to turn up a 10 underneath which would not affect the outcome whether I hit or not in the first place, but I just want to make sure that my thinking is correct.

 

dealer's up card was a 10, 5 was underneath

 

Good Play

The only hand that is a winning hand on the board besides the players blackjack is the 19 .The other 2 hands are dogs against the dealer up card of a 10.Your 12 actually is not that much of a difference between the 17 and 18 they can not hit where you should.But they do not realize that the 17 and 18 must hit there hands because if they get paid so does the 19 and Im assuming the 19 was now br3 and you were br 2 with a 12,So your decesion to hit the 12 was the right play because if you make 19 or better you are a sure winner.

 

Swog out late last night

Swog 39 % + 64 % = 103 % who gets the extra 3 % :laugh:

 

Thanks for the detail analysis. Now assume with the same scenario (I am chip leader and last to act), but the only difference this time is that the other three players hands are 17 or less and the dealer shows an 8 as upcard. Should I hit on hard 12 or wave off? The reason I ask is because I just encountered this similar scenario again yesterday on the last hand too. What happened was that I hit my 12 and busted, the dealer turns up a 4 underneath, hit a 10 and busted, so I didn't advance. I would think waving off is better this time because the only way I would lose is if the dealer have 17, which only happens 14% of the time.

 

Wong's CTS Book

Check-out Table 5 on page 131. It gives you a summary of what to do when you are BR1 and can win both ways. In this case, you are correct to stand.

 

Thanks for the tip. I didn't pay much attention to the tables in wong's book until now cause I am not a big fan of numbers.

 

Trying to apply my recent instruction in probability...

Hi

Hope you don't mind but I've started going back to look at old tournament teasers to see whether I can come to the same results as were originally posted. This is the first one I have done and I come up with a different solution. I've used my own infinite deck calculations based on my own spreadsheet but I must admit to having doubts on it's veracity.

Some of the calculations in previous posts assumed that we knew that the dealer did not have a BJ but of course we didn't until after the fact.

I have calculated that standing on the 12 rather than hitting to 19+ is the best strategy in this case. Hitting to 19+ is the second best strategy. Here is my working out which is based on my doubtful infinite deck calculations.

Here is the infinite deck maths;

Probability of hitting 17+ = 5 x 10.35% (i.e. 10.35% of hitting 17 plus 10.35% chance of hitting 18 and so on) = 51.75%
Probability of hitting 18+ = 4 x 11.14% = 44.56%
Probability of hitting 19+ = 3 x 12.00% = 36.00%
Probability of hitting 20+ = 2 x 12.92% = 25.85%
Probability of hitting 21 = 1 x 13.92% = 13.92%

If the above calculations are incorrect then there isn't any point going further.

If I stand my odds of advancing: i.e. the odds of the dealer hitting BJ, busting or hitting 20 or 21

Dealer BJ = 7.72%
Dealer Bust = 23.02%
Dealer 20 = 36.84%
Dealer 21 = 3.77%
Total =71.35%


If I hit to 19+ my chances of winning are the same as my chances of hitting to 19+ as I've locked up at least 2nd place. That means I win 36% of the time. Therefore you are 2 X more likely to win by standing than hitting to 19+. What do you think? What I have I missed?

Cheers

Reachy

 

Actually I've just re-read teh thread...

Still think it's better to stand (assuming we don't know the dealer doesn't have a BJ) but I've noticed that Monkeysystem's "hit the 12 one time" strategy is better than hitting to 19+, I think because you're more likely to bust if you try and get to 19+ which reduces your ways of winning.

Sorry for the constant posts guys.

Cheers

Reachy

 

Okay, more work required.

Reachy, let’s get you on the right track. I now you have the enthusiasm.
If you feel guilty of taking our time you can send some donation for a charity.

First about blackjacks.
In most calculations we assume the dealer has no blackjack. It simply is much easier for everybody.

Just kidding. In most cases if the dealer has a blackjack then the fate of the game is decided.
Darklord was the chip leader and everybody made max bets. The dealer had a Ten up, so nobody could take insurance. If the dealer had a blackjack all bets would be lost (except the other player who had a snapper himself) and whoever had the most unbet money would be the second advancing person.
In Darklord’s example studying what is the best play applies only to situations where the dealer doesn’t have a blackjack. Right?

Therefore, forget that 7.72% you included for standing on twelve.
Also, the numbers you planing to use for dealer probabilities are different if you assume that dealer has or has not bj. You should try to use dealers final results for the number of decks that were used in the real case, but often times when the number of decks are not specified the most common six-deck is used.
Some tables show probabilities for dealer’s Ten and Ace excluding blackjack and separately the chance for blackjack. Just add up all the percentage to find out if it equals 100%.
If you are using a table that shows percentages for dealer’s totals when dealer has bj, and you need to use numbers for dealer having no blackjack, you simply have to take all dealers outcomes and divide every one of them by (1- the chance for bj).

Later we can talk about "hitting to 19+" and comparisons of chances using ifinite deck calculations.

S. Yama

 

Still not sure why we should ignore the BJ odds?

Mr Yama, I was bought up in a fairly strict catholic family, I feel guilty about everything!!!!

I still can't understand why I should ignore the chance of the dealer having a BJ. When trying to figure out the odds of progressing to the next round surely we have to take into account every potential dealer outcome that might occur. A Dealer BJ is one of those situations and .... Oh hold on, I've just had a "penny dropping" moment. What you are saying is that regardless of mine or any of my competitors hands if the dealer has a BJ we all lose (unless they also have a BJ). So if the dealer has a BJ it's irrelevent what we do because we all lose anyway? I think I'm getting it now.

Thanks again

Reachy

 

Calculations with dealer BJ are unnecessary

Reachy, perhaps you are only familiar with blackjack games having the European No-Hole-Card rule where a dealer blackjack is not known until after the hand has been played. (This is still the case on Global when the Ace is showing.)

In US land-based casinos, when the dealer has a blackjack it is revealed before the play of the hand. If a ten is up, the dealer immediately checks the hole card; if the ace is up, an insurance decision is received from each player in turn and then the hole card is checked. In either case when it’s a BJ the hole card is revealed and the hand is over.

So you see it is not just that we all lose anyway. Why calculate probabilities for various outcomes of a hand that is never played?

 

What do they do on Global Player?

Thanks Jackaroo

My only experience is Global Player and I think they play a modified european style (do they?)

However you have clarified it further for me jackaroo and I can honestly say that I understand why you don't calculate BJs.

Thanks for your patience

Cheers

Reachy

 

“Hitting to 19+”.

The numbers you posted for “hitting to 17” through “hitting to 21” show that you have perfected infinite deck calculations.

Let’s make sure we understand all the details of darklord's teaser and that we use the same nomenclature.
You could say, for example, hitting to at lest seventeen, or hitting to 17+, or you could just simply say hitting to seventeen – it all would mean the same. You hit your total of twelve and either you bust or you stay if it is seventeen or more, otherwise you hit it again.
Consequently, saying hitting to fourteen, starting with a total of twelve, means that after your next hit your will either bust, have fourteen or more and stand, or you get an Ace for a total of thirteen and will be hitting it once more.

If a specific total of your hand guarantees you advancement it doesn’t mean you need to hit to that total.
This is because in some cases you may benefit from the dealer busting against your stiff hand, or you may win the hand with a total that’s smaller than the one that guarantees you advancement.

There is one certainty when you are searching for a total you need to hit to.
If your chances of advancing using strategy hitting to total x are better than hitting to x-1, than hitting to any total that’s smaller than x is suboptimal.
The same principle is true in reverse. If hitting to x is better than hitting to x+1, then hitting to any total that is greater than x offers worse chances.

This means that when you check for the best play you may have to calculate chances for “no-bust” strategy (standing on a stiff hand is no-bust play). Then, check hitting to twelve. If it is a better play, you should continue and run the numbers for hitting to thirteen, and so on, until you find a play that performs worse. You know that the play before the trend reversed was the optimum play.
Experience is a big help in finding the right play without checking all possible plays. The usual suspects are seventeen, eighteen, and twelve or thirteen.

Let’s have you working on some numbers. You are okay working with spreadsheets, right?
Get dealer’s outcomes for double deck (six deck works as well in this case).
Calculate the chances for the player standing on twelve.
Use infinite deck to calculate the chances for hitting to thirteen.
If hitting to thirteen is a better play, then you need to compare it to hitting to fourteen, and possibly higher totals until you find the total that you shouldn’t hit to.

There are more than one way of writing formulas for calculating chances of winning. It is helpful to systemize it so you first go through all final outcomes by either player or the dealer.
In our case it could be: player stiff to eighteen/dealer bust plus dealer twenty to twenty-one, player eighteen/dealer seventeen, player nineteen to twenty-one/dealer anything, player bust/ dealer twenty to twenty-one.

S. Yama

 

You think you've got it sussed then...

Thanks Mr Yama

OK. I've had a look at the problem and here is what I think. I used 6 deck dealer outcomes because they were already in my spreadsheet, hope you don't mind.

I still think standing is best by just under 2%.

If you stand the odds of winning are 63.63%
If you hit to 13+ you win 56.54% of the time
14+ - 55.86%
15+ - 54.98%
16+ - 53.88%
17+ - 52.52%
18+ - 56.27%
19+ - 61.99%
20+ - 55.95%
21 - 48.88%

So if you're going to hit, aim for 19! I did my calculations differently from before because I was missing out an important element. What I do is use the dealer outcome tables and calculate the odds of winning for each dealer outcome then add them up. What I hadn't been doing was calculating what would happen if I was unsuccessful with my strategy. For example in the strategy of "hitting to 19" all I was calculating initially was the odds of winning IF I was successfull in hitting to at least 19. I wasn't taking account of the odds of winning if I bust trying to hit 19. In the latest calculations I have now added that in. So for a "19+" strategy the odds are successfully hitting 19+ (36%) PLUS the odds of winning if I bust trying to hit 19+ (25.99% i.e. dealer hitting 20 or 21 if I bust) = 61.99%.

Am I getting there?

Cheers

Reachy

 

getting closer

Reachy, using dealer's final results for six deck is okay. Once we are done with the numbers I will show you why in this case it doesn’t matter that much if you use the infinite deck, or six-deck or double-deck.

You are going in the right direction. You added chances of advancing when you bust and the dealer makes twenty and twenty-one.

The next step is to reread last paragraph in my previous post to find what you needed to have complete set of situations that would make the player advance.
Note that there are at least three different part to this calculation if you separate it by player’s final results. Here it is again.
“In our case it could be: player stiff to eighteen/dealer bust plus dealer twenty to twenty-one, player eighteen/dealer seventeen, player nineteen to twenty-one/dealer anything, player bust/ twenty to twenty-one.”
You will need to separate numbers for the player ending up with stiff to eighteen together, eighteen alone, nineteen to twenty-one together, and bust. Happy calculating.
Let me know if you need additional help with writing spreadsheet formulas.
What are the new numbers?

S. Y.

 

what if

YOU GUYS ARE DRIVING ME CRAZY MY ALTHIEMERS IS KICKING IN: