blackjack ?
 

IA friend asks: Is it +ev to double down with blackjack (a+10) if the dealer shows a 6? (His argument is that a 6 may bust more than 75% of the time to make the 4-2 favored over 3-2)

Re: blackjack ?
 

No.

Re: blackjack ?
 

[ QUOTE ]
IA friend asks: Is it +ev to double down with blackjack (a+10) if the dealer shows a 6? (His argument is that a 6 may bust more than 75% of the time to make the 4-2 favored over 3-2)

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You would need to be better than a 7-to-1 favorite to win the double, which means you must win over 87.5% of all unpushed hands, not just 75%. That's because if you lose, you lose the 1.5 bets that were already yours for the BJ, plus the 2 bets you have out for the double, for a total loss of 3.5 bets. If you win, you only win 0.5 bet more than you would have by just taking the 1.5 for the BJ. So you are giving odds of 3.5-to-0.5 or 7-to-1 by making this play.

This would never be correct by basic strategy or off the top of the deck. You would need an extremely high count, such as if all the unseen cards were known to be tens.

Re: blackjack ?
 

FYI: The dealer busts 42% of the time with a 6 showing.

Re: blackjack ?
 

Yeah, that is not going to be a good bet at all.

In the early 90's I played BJ in Atlantic City for 3 years hardcore after I already knew the game very well and thought I saw it all. Took a trip to Vegas and was at a $25 min. table where a lady had $200 on a bet and got a BJ. BUT, she decided to try her luck and double down. Some casinos won't let you do this but most should since it's a real sucker bet. Anyhow the dealer showed a 4 and the lady doubled and got a 10 for 21 (not BJ). Can't remember if the dealer made a hand or busted but if the dealer got 21 it would be a push.

I thought to myself wow, can't believe I would ever live to see that. It is one thing to see someone split 10's vs. a dealer 5 or 6 but to double a BJ that already pays 3 to 2 was mind blowing.

Re: blackjack ?
 

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His argument is that a 6 may bust more than 75% of the time to make the 4-2 favored over 3-2

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One problem is that it's 4-4 over 3-2. As BruceZ pointed out, that's 4-4 in the bush vs. 3-2 in hand.

Re: blackjack ?
 

Hello,

The EV of standing with BJ against 6 is +1.50 and the EV of double down is +0.54 for a full deck and typical online rules.

If you remove all fives your EV is +0.77
If you remove all aces your EV is +0.80

But if you remove all aces, fives, fours, sixes and threys then your EV will be +1.75 and you should double down! And in that case your EV for playing is almost +5%, which is both very good and unlikely...

/ Johnny

Re: blackjack ?
 

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The EV of standing with BJ against 6 is +1.50 and the EV of double down is +0.54 for a full deck and typical online rules.

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BJ against a 6 doesn't have an EV, it has a V.
EV's > 1?