Online blackjack & multiple hands

Here is the set up:

At an online casino, you are allowed to play multiple hands of BJ at once and varying the bet amount. Assuming the rules only give the house a very slight edge to begin with, would it be possible to use the added info to turn the game +EV? Theoretically, one could adjust play in some very marginal circumstances and improve their odds slightly. (If it is, then you could theoretically bet very large on the last hand and very small on the others).

I doubt anyone has a definitive answer here, but how would one even go about testing this.

A lot depends on the number of decks, when it reshuffles, AND the number of SHOES.

TableMaster (the video game system with the dealer on a big screen TV, and up to 5 players) supposedly uses a separate 6 deck shoe for each player, another for the dealer, and it reshuffles after every hand.

In that system, there is no additional information to be gained.

This technique is called depth-charging. It works, as long as you are playing one deck BJ with a low edge to begin with.

Quote: ThaddeusB

Here is the set up:

At an online casino, you are allowed to play multiple hands of BJ at once and varying the bet amount. Assuming the rules only give the house a very slight edge to begin with, would it be possible to use the added info to turn the game +EV? Theoretically, one could adjust play in some very marginal circumstances and improve their odds slightly. (If it is, then you could theoretically bet very large on the last hand and very small on the others).

I doubt anyone has a definitive answer here, but how would one even go about testing this.

Oh, it's been done before, talked about before, tested before, and played before. The technique only benefits you by being able to play the last hand(s) with the knowledge of what the first 10-15 cards out of the shoe were. (The cards dealt to each spot are, for all intents and purposes, all coming off the top of the deck.)

In a six-deck shoe, fifteen cards coming out of the deck can only alter the true count by +/- 2.5, and usually it will be much less; in fact, even +1/-1 would be relatively unusual (it would mean a running count of +6 or -6 after only fifteen cards). So your only benefit would be in altering basic strategy, and very few plays are significantly different with that modification: for instance, you stand on hard 16 vs. 10 in plus counts, but that won't help yopu very much: a gain of about a hundredth of a bet.

So the upshot is that the negative EV of that big bet off the top outweighs the gain in play accuracy. The play might be more significant in single deck games, but it still won't do you that much good. The ploy is essentially the same as flat-betting while counting; it's better than plain old basic strategy, but not by much. And you can NOT increase this effect by making the last bet massive, because doing so increases the overall -EV of your first-round bets.

Quote: mkl654321

. And you can NOT increase this effect by making the last bet massive, because doing so increases the overall -EV of your first-round bets.

Yes, you can. Assuming that your strategy variations are only applied to the last hand, because you don't see enough cards out until that, it makes sense to bet as much as possible on the last hand, and as few as possible on the others, because the last one is playing under a better house edge.

Look:
Say, you bet 5 hands, at $25/hand. If HA is 0.5%, you are loosing $0.625 per round.
If your smart play on the last hand improves your EV by 0.05% on the last hand, it saves you $0.0125 per round, for the combined HA of 0.49%.
But, if you were betting only $5 on 4 hands, and $105 on the last one, you would lose $0.1 on the first four, and $0.4725 on the last one under the same assumptions about house edge, your combined loss would be $0.5725 or 0.48%

Quote: dwheatley

This technique is called depth-charging. It works, as long as you are playing one deck BJ with a low edge to begin with.

A lot of online games have low EVs, but some are coy about the number of decks in their virtual game.

Thaddeus, you can assume a re-shuffle after every hand, but to determine the # decks in use, see the technique described in the Wizard's blackjack appendix 13.

Interesting stuff. Thanks for the replies.

Quote: weaselman

Yes, you can. Assuming that your strategy variations are only applied to the last hand, because you don't see enough cards out until that, it makes sense to bet as much as possible on the last hand, and as few as possible on the others, because the last one is playing under a better house edge.

Look:
Say, you bet 5 hands, at $25/hand. If HA is 0.5%, you are loosing $0.625 per round.
If your smart play on the last hand improves your EV by 0.05% on the last hand, it saves you $0.0125 per round, for the combined HA of 0.49%.
But, if you were betting only $5 on 4 hands, and $105 on the last one, you would lose $0.1 on the first four, and $0.4725 on the last one under the same assumptions about house edge, your combined loss would be $0.5725 or 0.48%

I'm not going to bother to trace out your math, other than to note that it seems that you're agreeing with me.

The simple test is, does the benefit of making a better basic strategy decision after having seen 15+ cards (on that final, large wager hand) outweigh the inherent house advantage off the top? Assuming a six deck shoe, you are fighting about a -0.70% EV, so you would have to get all of that back on that big hand. Given that the true count is almost never going to have varied much by that time, I seriously doubt that basic strategy variations alone will make back that -0.70%. Remember, most of the benefit from counting accrues from bet variation, NOT from basic strategy alterations. In fact, I seem to remember reading that flat-betting a single deck with basic strategy alterations yielded about an 0.5% gain for the player. The gain on the first hand out of a six-deck shoe would, logically, be even less.

I never said you'd get the advantage with this method. Just that the effect of a (small) decrease in the house edge, can indeed be made somewhat larger by betting unproportionally large amounts on the last hand.

The thing about playing multiple Blackjack hands is that it allows you more control at the table. You are responsible for more than one hand and you can use all of your cards accordingly. You may win big or lose big which is a problem. Lets say the dealer is showing a 10. On anything from a 12-16 you are in trouble, between a rock and a hard place. You could bust on all of these hands before it even gets to the dealer and if you don’t take a card he will be good enough to beat you with 17.