# Blackjack press?

#### Cardcounter

##### Well-Known Member
I was wondering if any body can give me a mathimatical analsis of blackjack press. Here how it works you make 2 equal bets and a press bet if all 4 of your cards are the same color you lose the press bet. If it is not you get to place the press bet on the hand you think or know has the best chance to win. If you win your hand with the press bet on you win the money you bet on your hand plus the press bet. Blackjack only pay even money.

#### dacium

##### Well-Known Member
Ok, the chance of loosing to 4 cards of same colour is (assuming 6 deck game):
1*155/311*154/310*153/309 = 12.26%.

Average value of a hand in blackjack is 49.5%, but since a blackjack pays 1:1, that lowers it by about 2.5% to 47%. The chance of winning at least one hand is 1-(0.47^2) = 77.9%.

so you have
12.26% will loose 1
32.1% will loose 1
77.9% will win 1, if you pick the right hand, else loose.

Standard deviation in blackjack is 1.3 and 1.4 for two hands. Meaning if you take the best hand, you will still only be correct 10% of the time more than you are incorrect. so about 77.9/2 -5 = 33.95% you pick the wrong hand, and 43.95 you pick the right hand.

So all up I would say you win 1:1 43.95% of the time and loose 1:1 the rest of the time, for a house edge of about 12.1%

this is a rough guesstimate only.

Obviously high counts would amplifty the rate at which the house edge favour you though. It would be interesting to see when it becomes profitable to bet. Only have to have 1 hand hit a 18/19/20 to win would be awesome.

#### Geoff Hall

##### Well-Known Member
House Edge

House edge, for perfect play, is roughly 0.5% although you do have to place 3 bets at the start of each round.

#### zengrifter

##### Banned
Why does Wong say it might be posi-EV for a smart player? zg

#### Geoff Hall

##### Well-Known Member
+'ve ev

zengrifter said:
Why does Wong say it might be posi-EV for a smart player? zg
I have my theories on this and did some further calculations yesterday.

With my theory, you can get +'ve ev situations, although it involves extra work at the table. These situations arise, independent of the 'count', but will depend greatly on the penetration of the shoe.

Of course, my theory may be different from Wong's.

#### Frankie

##### Well-Known Member
I'm confused but intrigued. Would love a private message if you would share your theory.

#### weavin42

##### Well-Known Member
zengrifter said:
Why does Wong say it might be posi-EV for a smart player? zg
Where did you read this? I couldn't find anything on this game. I would be interested in a basic strategy and what the house edge is exactly with optimal bs. Like if I have an 11 on one hand (with a dealer 5 or 6) and a natural on the other where should I place the "press bet"? I like the idea of adding extra money to hands with a +ev like double downs. Also, isn't the payout for a natural higher than 3:2 (1.5:1) with the press bet? The expected payout for a natural is 1.7764:1 when you always play the press side bet. My logic here is 77.46% of the time you get to use the press bet (according to dacium you lose the side bet 12.36% of the time). If you have one unit on the hand and 77.64% of one unit [average] on the side bet and then you are paid 1:1. Is there some flaws in my logic?

So now we have a game that pays 1.78:1 (average) for a naturals, but how much does it cost when you are forced to add the press bet to hands with -ev? Is it double the normal house edge minus the extra payout for a natural?

A bs for this side bet surely must be place the bet with the highest ev (sometimes least -ev). bjmath.com has every hand vs. dealer up card ev values. I would imagine you could figure out the house edge that way. You'd have to sit at the table with a whole chart to play optimally, if you are counting too, that might be a little suspicious. Hmm...maybe I will take the time to do this if there is some interest.

Josh

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#### Geoff Hall

##### Well-Known Member
Cbjn

zengrifter said:
September CBJN. zg
I think Wong has overlooked something in that article.

#### Cardcounter

##### Well-Known Member
Come on!

If you had a blackjack and a 11 vs a 5 or 6 with the press bet you always take the natural. The natural will win 100% of the time and the 11 vs 5-6 will only win 60% of the time. \$10 press bet Plus \$10 win equals \$20! Compare that to \$20*.6=\$12-\$20*.4=8 for a \$4 average win. A \$10 average win vs a \$4 average win what would you pick?

#### zengrifter

##### Banned
Geoff Hall said:
I think Wong has overlooked something in that article.
Wong says (MAYBE) -
• Two BJ bets lose at 2.9% each
• Press bet wins at 12%
There! zg

#### Geoff Hall

##### Well-Known Member
zengrifter said:
Wong says (MAYBE) -
• Two BJ bets lose at 2.9% each
• Press bet wins at 12%
There! zg
The value of the 'Press' bet is pretty much negated by the condition that you lose your 'Press' if you have 4 cards of the same color.

If you were allowed to 'Press' only the hands that you wanted to then the value of the 'press' bet jumps to around 24%. This would leave a +'ve figure of around 12%. I'm not sure but maybe Wong overlooked that players must 'Press' even if they have 2 bad hands i.e. 15 & 16. Alternatively, he may have overlooked the 'Same Color' compensation.

#### zengrifter

##### Banned
Geoff Hall said:
The value of the 'Press' bet is pretty much negated by the condition that you lose your 'Press' if you have 4 cards of the same color.

If you were allowed to 'Press' only the hands that you wanted to then the value of the 'press' bet jumps to around 24%. This would leave a +'ve figure of around 12%. I'm not sure but maybe Wong overlooked that players must 'Press' even if they have 2 bad hands i.e. 15 & 16. Alternatively, he may have overlooked the 'Same Color' compensation.
No, didn't overlook. Betting on the better hand = 24% edge, minus 4-card same color = -12% edge = +12% net +EV. MAYBE. zg

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#### weavin42

##### Well-Known Member
Cardcounter said:
If you had a blackjack and a 11 vs a 5 or 6 with the press bet you always take the natural. The natural will win 100% of the time and the 11 vs 5-6 will only win 60% of the time. \$10 press bet Plus \$10 win equals \$20! Compare that to \$20*.6=\$12-\$20*.4=8 for a \$4 average win. A \$10 average win vs a \$4 average win what would you pick?
Yeah, bad example. I guess the point I was trying to make is that you need to look at the ev for each hand and go from there and it's not always going to be intuitive. A blackjack may have been a bad choice but how about the decision for placing the press bet on a 20 or the 11? With the addition of the press bet, it becomes a quadruple down. How about an 11 or a split hand (say 9's vs 5 or 6)? I still think the ev charts are the best thing to look at for the press bet decision.

All in all, it's not any worse than a regular 6 deck shoe. I think the harrah's has changed some more rules for the worse but I need to double check that.

Josh

#### zengrifter

##### Banned
zengrifter said:
No, didn't overlook. Betting on the better hand = 24% edge, minus 4-card same color = -12% edge = +12% net +EV.
So +12% - (3% x2-hands) = +6%/3 bets = +2% starting EV with correct BJ-Press strategy.

So, its decided, yes? zg

#### Geoff Hall

##### Well-Known Member
zengrifter said:
So +12% - (3% x2-hands) = +6%/3 bets = +2% starting EV with correct BJ-Press strategy.

So, its decided, yes? zg
Hi Zen

The analysis I have only makes the value of the 'Press' bet roughly 12% to start with. The overall edge that I have is around 0.5% to the house.

#### zengrifter

##### Banned
Geoff Hall said:
The analysis I have only makes the value of the 'Press' bet roughly 12% to start with.
And Wong pegs it at double that BEFORE calc'ing the 4-card color loss. zg

#### Geoff Hall

##### Well-Known Member
zengrifter said:
And Wong pegs it at double that BEFORE calc'ing the 4-card color loss. zg
Wong has admitted an error on BJ21 GC boards. He and MathProf have got similar results to mine.

#### Kasi

##### Well-Known Member
Geoff Hall said:
Wong has admitted an error on BJ21 GC boards. He and MathProf have got similar results to mine.
God bless the child who has is own lol.

Nice job Geoff.

And then some :grin:

#### Geoff Hall

##### Well-Known Member
Kasi said:
God bless the child who has is own lol.

Nice job Geoff.

And then some :grin:
Hi Kasi,

In fairness, I did have the help of 2 independent experts who provided the analysis