Rummy Blackjack
Most casinos in Costa Rica have no blackjack at all, claiming it is illegal. Instead, they offer a blackjack-based game called Rummy. You can find the rules on my Odds site.
Before you get your hopes up about all the good rules, especially early surrender, I think they don't offset the no 3-2. I'm going to start working on an analysis, but if there are any bored mathematicians on the forum, feel free join in the fun and we'll compare results.
Quote: BigJerSo do they automatically pay a 21, 1:1 I assume, or do they wait until the round is over?
No. A 21-21 tie would be a push. Any winning 21 pays 1 to 1.
Quote: CrystalMathDo you get paid the highest rummy bonus that you qualify for, or are they cumulative?
I just asked myself that as I start to work on this. Knowing how casinos usually interpret rules in their own favor, let's say the player gets only the highest bonus he is entitled to. I think this issue would come into play with a suited 7-7-7 only.
This table shows my analysis for a six-deck game, assuming the player always goes for the bonus.
| Bonus | Pays | Combinations | Probability | Return |
|---|---|---|---|---|
| Three of a kind unsuited | 3 | 23328 | 0.004653 | 0.013960 |
| Straight flush | 3 | 9504 | 0.001896 | 0.005687 |
| Three of a kind suited | 5 | 1040 | 0.000207 | 0.001037 |
| 7-7-7 unsuited | 5 | 1944 | 0.000388 | 0.001939 |
| 6-7-8 suited | 5 | 864 | 0.000172 | 0.000862 |
| Total | 36680 | 0.007317 | 0.023485 |
I'll obviously have to take into account that the player won't always go for the bonus.
Quote: WizardLet me say that my rough estimate for now shows a house edge of right about 1%. I'd give it +/- 0.1%.
Offhand it looks like with no blackjacks there is no way to count the game.
Rule variants
The following rule variants may be encountered in Rummy.
I am confused by this rule variant : Unsuited 7-7-7 pays 3 to 1 bonus only.
If the general rule is: Unsuited Three of a kind pays 3 to 1 is the exception that only 7-7-7 pays 3 to 1 , and every other unsuited three of a kind pays nothing?
Can you double the A-10 to get a 3 card 21? If not, can you hit it for a 3 card 21?
My guess is no for all of the above.
Quote: pacomartinI am confused by this rule variant : Unsuited 7-7-7 pays 3 to 1 bonus only.
Sorry for the confusion. I meant to say that a suited 6-7-8 pays 3 to 1. However, I decided to remove mention of it from the list. As far as I know, only the Marriot in Jaco applies that rule, and they also apply every other unfavorable rule variant.
Quote:Other questions: If you double and make a rummy hand, do you get paid on both bets? (ie, Double down on 5-5 and get another 5, or double 5-6 get a 4 or 7 )
Good question, which I didn't think to ask while there. I would assume the bonus applies to the original bet only.
Quote:Can you double the A-10 to get a 3 card 21? If not, can you hit it for a 3 card 21?
Yes. When you get A-10 the dealer will wait on you to make a decision. I see no up-side to hitting A-10.
Quote: WizardSorry for the confusion. I meant to say that a suited 6-7-8 pays 3 to 1. However, I decided to remove mention of it from the list. As far as I know, only the Marriot in Jaco applies that rule, and they also apply every other unfavorable rule variant.
Good question, which I didn't think to ask while there. I would assume the bonus applies to the original bet only.
Yes. When you get A-10 the dealer will wait on you to make a decision. I see no up-side to hitting A-10.
When I was there 15 years ago the bonus was paid on the doubled amount,if that is still true,it might be correct to double 6,6 against 2 or 3 and 4,4 against 2thru 6 but am not sure.
Quote: HunterhillWhen I was there 15 years ago the bonus was paid on the doubled amount,if that is still true,it might be correct to double 6,6 against 2 or 3 and 4,4 against 2thru 6 but am not sure.
Damn. My hunch is that you still wouldn't double on 6-6 ever, but this would increase the EV when doubling 5-5. I know of a couple people in CR I can ask to ask about it.
Quote: Wizard
Yes. When you get A-10 the dealer will wait on you to make a decision. I see no up-side to hitting A-10.
The only time I can think this might make sense is if you have a suited AK or AQ and shooting for the remaining card to a straight flush. You probably wouldn't do this all the time, but maybe against a 5 or 6?
edit: What about an 888? Do you get paid the bonus and then lose your original bet because you busted?
Quote: CrystalMathIf you get a 678 or 777, you get paid the bonus immediately. Is your turn over now, or do you continue to play against the dealer?
You continue to play against the dealer.
Quote: WizardMost casinos in Costa Rica have no blackjack at all, claiming it is illegal. Instead, they offer a blackjack-based game called Rummy.
Give them credit now, you always said you were OK with this stuff as long as they don't call it Blackjack.
Quote: odiousgambitGive them credit now, you always said you were OK with this stuff as long as they don't call it Blackjack.
I do. In my opinion only games that pay 3-2 on a blackjack are entitled to be called blackjack.
Quote: HunterhillJust looked over my notes.Some casinos paid 4 to 1 on 3 of a kind if the hand busted ie... 888 999,also 6,7,8 is paid 3 to 1 or 5 to1 if suited. This was 15 years ago so it very well could have changed. I played in 9 casinos while I was there.Some of the casinos would deal blackjack if enough players wanted to play that instead of Rommy. In one very small casino The cage did not have enough money to pay us when we cashed out so they took the drop boxes off of the tables to get the rest of the money.
I never saw a 4 to 1 bonus for anything. What you see on my site is what I saw last week. I hope paigowdan manages to find this thread, as I think he has been to CR fairly recently. At the Cocal Casino in Jaco (quite a place) they didn't have enough chips in the rack to pay me when I wanted to leave so wrote a voucher for me to take to the cage.
Quote: CrystalMathThe only time I can think this might make sense is if you have a suited AK or AQ and shooting for the remaining card to a straight flush. You probably wouldn't do this all the time, but maybe against a 5 or 6?
I've calculated this, and you would never hit an A/10.
Quote: CrystalMathI've calculated this, and you would never hit an A/10.
I agree, and was confused by the "3 card 21" column, and thought you got a bonus on all 3 card 21s of 5 to 1, which would indeed make doubling (or hitting) profitable. My mistake.
Quote: HunterhillWhen I was there 15 years ago the bonus was paid on the doubled amount,if that is still true,it might be correct to double 6,6 against 2 or 3 and 4,4 against 2thru 6 but am not sure.
If the rummy bonus pays on the entire bet (which I have read on other forums too), then you will double suited 6s versus a 3 or a 5 and any 6s versus a 4.
You will also double 4s against 2 through 6.
Quote: CrystalMathIf the rummy bonus pays on the entire bet (which I have read on other forums too), then you will double suited 6s versus a 3 or a 5 and any 6s versus a 4.
You will also double 4s against 2 through 6.
Can you elaborate on what other forums say on this topic? Based on the evidence you've seen, what is the probability you think the bonus is based on the full doubled bet? Can you provide any links to other forums on this topic?
Quote: WizardCan you elaborate on what other forums say on this topic? Based on the evidence you've seen, what is the probability you think the bonus is based on the full doubled bet? Can you provide any links to other forums on this topic?
This is on BJ21.com: BJ21 Rummy Post
This is nearly 9 years old.
I think there is an excellent chance that this has been done in the past, but I can't find any current info. I suppose it could be a rule variation.
I have also read many times that a busted rummy (888 for instance) pays 4-1, and on at least one site, I've read of increased rummy pays of 4/7 instead of 3/5.
I'm really hoping that you can get some great info from any Costa Rican contacts.
In addition to that, I just called the former owner of a CR casino who said the bonus is indeed applied to the FULL doubled bet.
However, on the day we arrived, our hotel was right next to a casino, so I checked it out. I was going to play Rummy, but then I realized the House Edge must be pretty high, and if the game has a high edge I'd rather play a game with plenty of variance, so I didn't play.
I'm no mathematician, so I'm wondering if my assumption that the lack of Blackjacks paying 3 to 2 would create too huge an edge for the bonuses to make up for was right.
Quote: WizardLet me say that my rough estimate for now shows a house edge of right about 1%. I'd give it +/- 0.1%.
I'm at 1.02%.
Quote: CrystalMathI'm at 1.02%.
Good to hear! Cindy Liu (non forum member) is also getting right around 1%. I appreciate your confirmation. I hope to have a strategy and more details up on my Odds site early next week.
Player Dealer's Card
Hard 2 3 4 5 6 7 8 9 10 A
4-6
7 H H H H H H H H H Rh* *Hit on 34 Suited
8 H H H H* H* H H H H H *Double on 35 suited
9 H* D D D D H* H H H H *Double on 45 suited
10 D D D D D D D D H H
11 D D D D D D D D H* H *Double on 56 suited
12 H H S* S* S* H H H H Rh* *Hit on 57 suited, hit 2Tv5
13 S* S* S* S* S* H H H H Rh* *Hit on 67 suited
14 S S S S S H H H H* Rh *Surrender 68 unsuited
15 S S S S S H H H Rh* Rh* *Hit on 78 suited
16 S S S S S H H Rh* Rh Rh* *Hit on 79 suited
17 S S S S S S S* S S Rs *Hit on 89 suited
18+ S S S S S S S S S S
Soft 2 3 4 5 6 7 8 9 10 A
13 H H H* D D H H H H H *Double on A2 suited
14 H H H D D H H H H H
15 H H D D D H H H H H
16 H H D D D H H H H H
17 H D D D D H H H H H
18 S D D D D S S H H H
19+ S S S S S S S S S S
Splits 2 3 4 5 6 7 8 9 10 A
2,2 H H H H H H H H H H
3,3 H H H H H H H H H H
4,4 D D D D D H H H H H
5,5 D D D D D D D D D H
6,6 H H* D PDh* PDh H H H H H *Double on 66 suited
7,7 H D PDh PDh PDh H H H H H
8,8 P P Ph Ph Ph Ph Ph H H H
9,9 P P P P P S P P S S
10,10 S S S S S S S S S S
A,A PDh PDh PDh PDh PDh Ph Ph Ph Ph Ph
Who?Quote: WizardCindy Liu
Sorry . . . that was an irresistible impulse.
Quote: CrystalMathHere's my strategy
Thanks, this is outstanding! Not considering the bonuses, it agrees with my strategy. It also lines up well with the Cindy Liu strategy, except she is still working on the bonus exceptions.
A huge thanks to CM for this help!
