Known Ten gone Wrong Blackjack

Assume you know the first card dealt to you in Blackjack is an Ace. Your edge will be roughly +51% rule depending
if the first card is a ten its about 13%

but what if i know the dealers upcard before the round is an Ace or a ten? how much -EV is that.
i heard a dealers ace is -35% but dont know about the ten? basically i want to know what happens if my known card goes wrong.

Any suggestions on the answer ? book or online sources to find the answer are also very welcome.

thank for the help Dagobert

Quote: Dagobert

Assume you know the first card dealt to you in Blackjack is an Ace. Your edge will be roughly +51% rule depending
if the first card is a ten its about 13%

but what if i know the dealers upcard before the round is an Ace or a ten? how much -EV is that.
i heard a dealers ace is -35% but dont know about the ten? basically i want to know what happens if my known card goes wrong.

Any suggestions on the answer ? book or online sources to find the answer are also very welcome.

thank for the help Dagobert
link to original post

https://wizardofodds.com/games/blackjack/expected-values/
The Wizards appendices at the link above give you everything you need to know to answer this question and many others. You can easily copy and past a table to a spreadsheet. Just add a formula to the next column to select the highest EV from the available strategy choices for the Dealer Ace rows. Then multiply this EV by the probability column to weight the hand properly. The sum of this weighted EV divided by the sum of the probabilities is the EV of the situation where all you know is that the Dealer will have an Ace up.

If you can do this calculation yourself, you will learn more than just asking someone for a number.

Edit: you need to divided the probability for hands where dealer has BJ by 2. Only half the hands where deal has BJ have an Ace up.

Even if you don't know for sure that the first card dealt to you will be whatever, if you know what you are doing and know every card that has come out so far and the count you can know whether there is an increased probability that your first card will be a 10/face, based on not just the count but on what cards have come out in the latest sequence. It doesn't take a genius to understand what the best sort of prior sequence would be. And then of course you need to be seated so that that first card will be yours. Whether I am playing at a private table or not I always prefer first base seating.

Sometimes though the dealer will end up with the 10 up, and you'll get a hard 16 or such, with a million expected 10/faces coming. 🤷🏻‍♂️ At that point the ability to tell the dealer to take that stiff and pound it up his a** is helpful.


What get outta here?
I got a marker comin'. Deal.

not sure how that adresses the question but thanks for the reply

thanks for the reply
unfortunately I believe that sth about this data set is of.

/games/blackjack/appendix/9/euro-6ds17r4/
was working on this rule set but the probabilty of all hand combinations should add up to 100% and it only adds to 95.25%

so some probabilities are either wrong or sth is missing.

greets

also on average the probability of a ten up is 4/13 = 30.77% but in this data set probability of all ten up scenarios is 28.39%

I have to give you credit for trying. Most people won't try to develop the tools and ability to answer their own questions. This is the EV for every dealer up card. The table below was generated using Eric Farmer's BJ code. You will need to multiply the EV for dealer Ten by 4 and then divide the sum by 13 to get the correct overall EV.

I think you are close to getting the spreadsheet right. The reason that you don't get 100% is that the way Mike presents the tables requires you to correct the dealer blackjack probabilities. Mike gives you the probabilities for a hand like Ace up vs 7,8, but then he lumps a dealer blackjack with Ace up together with blackjack with Ten up. If you are looking specifically for EV versus dealer Ace up or Ten up, you have to divide the Dealer BJ probabilities by two. You could just create two extra lines in your spreadsheet with Ace up and Ten up and half the probability.

If you make this correction, you should get the total probability for dealer ace as 0.0070765951 = 1/13. I get the overall probability as 0.99999921 which is not 1.00 due to adding many rounded numbers.

There are different numbers of columns for the different tables. I use the maximum function to get the max EV into an additional column. For example =MAX(E3;G3;I3) when there are three columns.

I have a column with the formula =IF(A8=$K$2;1;0) in row 8 where column A has the value A, 2, etc, and $K$2 has one of these values. If I multiply the probability and EV columns by this formula, it selects out just whatever deal up card is entered into the cell $K$2. Then, if I want to see the EV versus Dealer 4, I get it immediately after entering a 4 into cell K2.

Quote: Dagobert

thanks for the reply
unfortunately I believe that sth about this data set is of.

/games/blackjack/appendix/9/euro-6ds17r4/
was working on this rule set but the probabilty of all hand combinations should add up to 100% and it only adds to 95.25%

so some probabilities are either wrong or sth is missing.

greets
link to original post

Fixing the link to:
https://wizardofodds.com/games/blackjack/appendix/9/euro-6ds17r4/

8 decks, H17, DOA, DAS, SPL3, NRSA, surrender

Known Ten vs Ten, EV = -0.6451%
Known Ten vs Ace, EV = -22.85%

Known Ten vs Any upcard, EV = 14.14%

Thanks I ll see if I can build a model that gets close to these numbers
I do appreciate your input to help me how to think which is the most important in the long run.
Thanks a lot

Thanks for the reply