# Blackjack: Doubling bet: Why doesn't it work? **URL:** \ **Category:** Factual Questions\ **Created:** [December 6, 2004, 7:36am UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335 "2004-12-06T07:36:10Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Spoke](https://avatars.discourse-cdn.com/v4/letter/s/a88e57/32.png) [@Spoke](https://boards.straightdope.com/u/Spoke)\ **Post date:** [December 8, 2004, 9:08pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/41 "2004-12-08T21:08:41Z")
> [@CurtC](#): > > According to your definition of “unusual.” A particular hand in BJ will be independent of the one before it (streaks don’t exist except in retrospect). If the probability of winning is 49.5%, then the probability of getting a 40-hand losing streak is about 1.4 times out of a _trillion_. The prob of a 40-hand winning streak is about 0.6 times out of a trillion. You must play a LOT of blackjack. Maybe he just plays very poorly? 😉 “18? _Hit me!_” (Kidding, **jasonh300** , kidding.) ---
**Author:** ![Giles](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/giles/32/60_2.png) [@Giles](https://boards.straightdope.com/u/Giles)\ **Post date:** [December 8, 2004, 9:15pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/42 "2004-12-08T21:15:37Z")
> [@Left Hand of Dorkness](#): > > I just realized that I was counting on my fingers to figure out the odds on that one. Heh. At least counting exponents isn’t as embarrassing as counting units. > Daniel You have 1,000 fingers? ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [December 8, 2004, 9:17pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/43 "2004-12-08T21:17:40Z")
> [@Munch](#): > > Yes, but NOT taking odds bets considerably lowers your odds, don’t they? It depends on how you define “odds.” As a ratio of your bet, the house advantage goes down, but only because the amount of your bet is larger - the expected value of how much you will win is still exactly the same. The house advantage is usually defined as the house’s expected winnings divided by your bet. Taking the odds bet increases the denominator, but doesn’t change the numerator, therefore making the house advantage smaller. However, it does _not_ make you more money over the long term. A confusing distinction to most people, and casinos take advantage of this confusion by advertising “10X ODDS!!!” and such. > [@muttrox](#): > > _re: 2:1 payout on blackjack_ > Your conclusions doesn’t follow from this example. Yes, the casino has made the odds slightly better than “standard”. It does not follow that the odds are in the players favor. Lessee - scribble scribble - it looks like you can expect to get a blackjack about one out of 20 hands, and will gain an extra 50 cents per dollar bet when you do. So playing this way increases your expectation by about 2.5 cents per hand, easily moving your expectation into the black if you know basic strategy. ---
**Author:** ![iamthewalrus\_3](https://avatars.discourse-cdn.com/v4/letter/i/258eb7/32.png) [@iamthewalrus\_3](https://boards.straightdope.com/u/iamthewalrus_3)\ **Post date:** [December 8, 2004, 10:10pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/44 "2004-12-08T22:10:09Z")
> [@mazinger\_z](#): > > Actually, I was doing the math on the back of this envelope, but now I have to run to a meeting; however, I found this site: [Blackjack Odds - Advantage Calculator](http://www.qfit.com/blackjack-odds-calculator.htm) > > Paying 2 to 1 is probably the best advantage given to a player, making 6 deck shoes, no resplitting As worthwhile to play. > > Btw, 6 to 5 pay off on the natural is probably the most evil thing that casinos have done, even on 1 deck. (Note to all: do not play this game!) Why does the number of decks matter if you’re just playing basic strategy? ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [December 9, 2004, 5:17pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/45 "2004-12-09T17:17:34Z")
> [@Munch](#): > > How many people do you see at a craps table who don’t take advantage of odds bets simply because they don’t know about them? There may well be lots of players who use a sub-optimal strategy and thus increase the casino’s advantage. But there is no craps strategy that gives a player the advantage over the casino. And there is no advice the _croupier_ can provide that isn’t available to a player who simply spends 10 minutes studying the rules. So taking advice from others (be they never so savvy) still leaves you a long-term loser. If you pay for that advice (through tips) you lose even more. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [December 9, 2004, 5:28pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/46 "2004-12-09T17:28:34Z")
> [@mazinger\_z](#): > > There are still professional blackjack players, they have to move around often, because they do not want to be known. My (admittedly limited) information on this came from a guy who used to work at a Reno casino (I think it was the Hilton). He said that dealers were trained to look for the betting patterns that indicate card counting, and to notify management if they spotted anything suspicious. Managers would have a “talk” with such players, which often included an invitation to leave and not return. There apparently exists a sort of “black list,” accessible to all casinos, with names and photos of counters. You seem to have a lot of experience, and are saying that card counting and winning up to $2k a week can pass “under the radar” of casinos. If so, that’s quite interesting (not to say tempting). ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [December 9, 2004, 5:35pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/47 "2004-12-09T17:35:33Z")
> [@duffer](#): > > when it comes to a casino, _everyone_ is looking to make money. Very true. The catch is that only one small group is actually doing so: the casino owners. ---
**Author:** ![Munch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/munch/32/5281_2.png) [@Munch](https://boards.straightdope.com/u/Munch)\ **Post date:** [December 9, 2004, 6:20pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/48 "2004-12-09T18:20:34Z")
> [@Xema](#): > > There may well be lots of players who use a sub-optimal strategy and thus increase the casino’s advantage. But there is no craps strategy that gives a player the advantage over the casino. And there is no advice the _croupier_ can provide that isn’t available to a player who simply spends 10 minutes studying the rules. > > So taking advice from others (be they never so savvy) still leaves you a long-term loser. If you pay for that advice (through tips) you lose even more. You took my original use of the word “advantage” in the wrong way. Sorry for the confusion. I never intended to suggest that taking the odds in craps gives a player the advantage over the house. It merely reduces the rate of your loss with a limited budget - which is certainly an advantage over losing your money immediately in terms of enjoyment. ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [December 9, 2004, 6:54pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/49 "2004-12-09T18:54:02Z")
> [@Munch](#): > > I never intended to suggest that taking the odds in craps gives a player the advantage over the house. It merely reduces the rate of your loss with a limited budget - which is certainly an advantage over losing your money immediately in terms of enjoyment. Like I posted earlier, this depends on how you look at it. It’s true that betting $5 on the pass line, plus $10 as an odds bet, is better than betting $15 on the pass line. But just comparing the $5 on the pass line scenario, your expected winnings (the average you could expect over a long term) are exactly the same whether you put odds behind the bet, or don’t. That’s why I think it’s not correct to state that the odds bet improves your chances of winning. ---
**Author:** ![Munch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/munch/32/5281_2.png) [@Munch](https://boards.straightdope.com/u/Munch)\ **Post date:** [December 9, 2004, 7:47pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/50 "2004-12-09T19:47:56Z")
> [@CurtC](#): > > Like I posted earlier, this depends on how you look at it. It’s true that betting $5 on the pass line, plus $10 as an odds bet, is better than betting $15 on the pass line. But just comparing the $5 on the pass line scenario, your expected winnings (the average you could expect over a long term) are exactly the same whether you put odds behind the bet, or don’t. That’s why I think it’s not correct to state that the odds bet improves your chances of winning. That’s why I was careful in what I said. I didn’t say it increases your odds - it just increases your playing time (assuming a consistent rate of gambling), and thus your enjoyment. ---
**Author:** ![mazinger\_z](https://avatars.discourse-cdn.com/v4/letter/m/5f9b8f/32.png) [@mazinger\_z](https://boards.straightdope.com/u/mazinger_z)\ **Post date:** [December 9, 2004, 7:56pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/51 "2004-12-09T19:56:05Z")
> [@iamthewalrus(:3=](#): > > Why does the number of decks matter if you’re just playing basic strategy? I believe this has to do with event expectation. Even if you’re not counting, there is a certain event expectation that comes about during certain card combination/plays. For instance, I think the perrenial example to this question is that when you have 7-7 against a 10 card, you hit if you are playing multi-deck because there are more chances/expectation of getting a card that won’t bust you. If you are playing single deck, you would stand, b/c stiff hands (even though you can split here, it is not advisable that you do b/c this is not one of the scenarios where you don’t want more money on the table) are not good for the player. Playing single deck will get you more stiff hands (and more naturals), and it is better to stand and see if the dealer also has a stiff and make them take a card. If you’re counting, and they make their hand with low cards, this is good b/c it ups the count and you can throw more money on the table. ---
**Author:** ![Left\_Hand\_of\_Dorkness](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/left_hand_of_dorkness/32/7156_2.png) [@Left\_Hand\_of\_Dorkness](https://boards.straightdope.com/u/Left_Hand_of_Dorkness)\ **Post date:** [December 9, 2004, 8:20pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/52 "2004-12-09T20:20:30Z")
> [@Giles](#): > > You have 1,000 fingers? Who do you think I am, Dr. Terwilliger? Nah. When I was a kid, someone taught me to count to 1,023 on my fingers. Treat 'em as binars instead of digits, and you’re set. Daniel ---
**Author:** ![jasonh300](https://avatars.discourse-cdn.com/v4/letter/j/46a35a/32.png) [@jasonh300](https://boards.straightdope.com/u/jasonh300)\ **Post date:** [December 9, 2004, 10:34pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/53 "2004-12-09T22:34:57Z")
> [@Xema](#): > > Outside of special (and presumably unusual) promotions like you describe, how can there be a “professional” blackjack player? Previous threads have described how counting cards is theoretically advantageous but doesn’t work in practice (basically, because it’s easy for casinos to detect and to frustrate). So how can anyone (except a casino owner) make money playing blackjack? There are teams of professional card counters that can and do make money playing blackjack. There aren’t many that are successful and the casinos give them problems, but I know two brothers that built a team about 5 years ago that are now worth millions just from playing blackjack. They have a higher mathematical ability than the average person and have an uncanny ability to memorize strategy tables, but are far from genius. If it card counting didn’t work in practice, the casinos wouldn’t sweat when they know card counters are on the premesis. One of the keys is to play short sessions in casinos and get the hell out and not return to that casino for a while (like 6 months to a year). There are thousands of casinos in the US to choose from, so they can do that. The advantage of a team is that there are 5 or 6 people and they’re never seen together in public so when the first guy gets out of the casino, the next guy can go in and so on. As long as they remain inconspicuous, they can take small amounts of money away from the casino without ever being noticed. ---
**Author:** ![jasonh300](https://avatars.discourse-cdn.com/v4/letter/j/46a35a/32.png) [@jasonh300](https://boards.straightdope.com/u/jasonh300)\ **Post date:** [December 9, 2004, 10:42pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/54 "2004-12-09T22:42:55Z")
> [@Xema](#): > > Can you describe how it would work better for Bacarrat? > > I don’t think it (or any “system”) can work when the odds are rigged against the player (as they are in all casinos). And if you’re playing a game in which the odds are in your favor, you don’t need a system. I didn’t say it WOULD work for Bacarrat. I just meant that the strings of winning or losing hands don’t seem to go as long as they do for blackjack. Win or loss is _almost_ 50/50 in bacarrat, as it is for betting black and red on roulette. Blackjack has many different factors that determine a win or a loss which is why it’s possible to win or lose many, many hands in a row at blackjack. Then again, I watched a roulette wheel roll black all the way down the scoreboard (which I think shows the last 20 numbers). If you were using the martingale system on that betting red, you’d be betting around 1 million dollars on the 20th roll. ---
**Author:** ![jasonh300](https://avatars.discourse-cdn.com/v4/letter/j/46a35a/32.png) [@jasonh300](https://boards.straightdope.com/u/jasonh300)\ **Post date:** [December 9, 2004, 10:55pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/55 "2004-12-09T22:55:13Z")
> [@CurtC](#): > > According to your definition of “unusual.” A particular hand in BJ will be independent of the one before it (streaks don’t exist except in retrospect). If the probability of winning is 49.5%, then the probability of getting a 40-hand losing streak is about 1.4 times out of a _trillion_. The prob of a 40-hand winning streak is about 0.6 times out of a trillion. You must play a LOT of blackjack. Blackjack probability doesn’t work quite like that. It’s not like flipping a coin. On certain hands (player has 2 cards, dealer is showing one card), the odds vary. What the player does next (hit, stand, double, split) varies those odds drastically. I’m quoting all of this from memory, because I haven’t played any blackjack in a few years or read any books on the subject. There is a book on blackjack, written by a mathematician that takes all of the different playing rules that the casino uses and different strategy tables that adapt to those rules. In the appendix, there was a lenghty table of probability, including the probability of winning and losing different numbers hands in a row. The numbers are surprising, but based on the rules, the math seems to be correct. I’ll try to dig that book up and give exact numbers. ---
**Author:** ![EllisDee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ellisdee/32/4531_2.png) [@EllisDee](https://boards.straightdope.com/u/EllisDee)\ **Post date:** [December 10, 2004, 4:17am UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/56 "2004-12-10T04:17:30Z")
> [@Munch](#): > > You took my original use of the word “advantage” in the wrong way. Sorry for the confusion. I never intended to suggest that taking the odds in craps gives a player the advantage over the house. It merely reduces the rate of your loss with a limited budget - which is certainly an advantage over losing your money immediately in terms of enjoyment. Odds serve no purpose whatsoever except to increase your variance. That has exactly one effect: you reach your loss limit faster. Odds in no way affect the expectation; they have none. The line bets retain their original expected value, and the odds carry zero expectation, thus 1.41% (or 1.40%) plus zero is still 1.41%. (or 1.40%.) So when you play odds, all you are doing is shortening your lifespan at the table. Yet countless other gamblers love to tell me about how I’m failing to take advantage of the odds, without realizing that they are the ones being taken advantage of. Regarding the Martingale as a concept, here’s my standard (streamlined) debunker: Let’s assume 50-50 wagers. Say, a coin flip. What’s the chance to lose 3 in a row? 12.5% So I lose 2 in a row. Now I should bump, because there’s a 100 - 12.5 = 87.5% chance to win, right? Wrong. You just lost 2 in a row, which in itself only has a 25% chance to occur. That means that you already realized the low percentage chance you are trying to capitalize on. As in, you missed your chance. Once you lose 2 in a row, you have painted yourself into a 25% total probability zone: 12.5% of the time you win, 12.5% of the time you lose, and 75% of the time you never got here in the first place. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 10, 2004, 6:39am UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/57 "2004-12-10T06:39:25Z")
> [@](#): > > Odds serve no purpose whatsoever except to increase your variance. Precisely why they’re desireable. If you don’t want variance, then what are you doing in a casino in the first place? If you want a low variance game, you can’t beat “put the money in your pocket and leave it there”. Better odds than anything in Vegas, too. But if people are willing to pay for variance (essentially what you’re doing, when you bet in a casino), then why not take some free variance while you’re at it? ---
**Author:** ![EllisDee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ellisdee/32/4531_2.png) [@EllisDee](https://boards.straightdope.com/u/EllisDee)\ **Post date:** [December 12, 2004, 1:43am UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/58 "2004-12-12T01:43:18Z")
> [@Chronos](#): > > Precisely why they’re desireable. If you don’t want variance, then what are you doing in a casino in the first place? If you want a low variance game, you can’t beat “put the money in your pocket and leave it there”. Better odds than anything in Vegas, too. But if people are willing to pay for variance (essentially what you’re doing, when you bet in a casino), then why not take some free variance while you’re at it? You’re missing the forest for the trees. If I walk into a casino with $300, would I be better off playing blackjack at the $100 table or the $10 table? Obviously the latter, despite the former having more variance. For the same reason, you are better off not playing odds at craps. ---
**Author:** ![muttrox](https://avatars.discourse-cdn.com/v4/letter/m/a8b319/32.png) [@muttrox](https://boards.straightdope.com/u/muttrox)\ **Post date:** [December 13, 2004, 1:20pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/59 "2004-12-13T13:20:11Z")
> [@Ellis Dee](#): > > You’re missing the forest for the trees. If I walk into a casino with $300, would I be better off playing blackjack at the $100 table or the $10 table? Obviously the latter, despite the former having more variance. For the same reason, you are better off not playing odds at craps. I disagree. Your best bet is to put every red cent you have down on one hand. You have a just under 50% chance of doubling your money. If you grind that out over 1,000 hands, you have a close to zero chance of doubling your money. ---
**Author:** ![Bricker](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@Bricker](https://boards.straightdope.com/u/Bricker)\ **Post date:** [December 13, 2004, 1:38pm UTC](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335/60 "2004-12-13T13:38:36Z")
> [@jasonh300](#): > > The advantage of a team is that there are 5 or 6 people and they’re never seen together in public so when the first guy gets out of the casino, the next guy can go in and so on. As long as they remain inconspicuous, they can take small amounts of money away from the casino without ever being noticed. To expand a bit, the casino can detect counting because there is some obvious behavior asscoiated with it: at least some level of concentration, no drinking, etc – plus, of course, raising your bet when the count favors the player and playing the minimum when the count does not. The team approach frustrates the casino’s observation because the counter does NOT do any of those things. He plods along, playing the minimum hand, and standard basic strategy – just like a zillion other players. But he is ALSO counting, and when the count is good for the player, he ever-so-invisibly sets a signal for the “gorilla” to come by. This is a loud, boisterous, drinking a little bit player who plops down at the table and starts making huge bets right away – exactly the kind of player the casino normally loves. Of course, because the count is good, the “gorilla” usually wins big, and he gets up and lurches away to cash in, the recipient of a “lucky” streak. Meanwhile the actual counter plods ahead with his minimum bets and his lemon Perrier. [Previous page](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335.md?page=2) [Next page](https://boards.straightdope.com/t/blackjack-doubling-bet-why-doesnt-it-work/278335.md?page=4)