Error pays 3:2 on ALL 21's for now

There is blackjack machine that I was playing for the purpose of earning comps. And the rules are pretty decent-

H17, DOA, DAS, LS, and 3:2. (But, while running money thru this machine I discovered it was paying 3:2 on ALL 21's!!!)

Is this glitch large enough to make the machine +EV? How much? How should I alter basic strategy?

wow.
Can't do the maths, but I feel it must be +ev

I wouldn't alter basic strategy too much - but I'd spend some time at that machine...

My guess is the changes are when the player has 12-14 and dealer has 12-14?

btw, side note, wouldn't it be great if the machine took 1.5 times your bet if you lose to 21 to "make up" for it? Just a stupid little thought...

If you double for 21, do you get 3:2 on your initial bet and your double down as well?

Where do I sign up for this?

What's the most you can bet at a time? Is it on one machine or a bank?

Quote: OnceDear

wow.
Can't do the maths, but I feel it must be +ev

Mathematically, I believe it's in the neighborhood of, "I'm wearing Depends and can stay awake for 72 hours"
:)

Quote: HowMany

There is blackjack machine that I was playing for the purpose of earning comps. And the rules are pretty decent-

H17, DOA, DAS, LS, and 3:2. (But, while running money thru this machine I discovered it was paying 3:2 on ALL 21's!!!)

Is this glitch large enough to make the machine +EV? How much? How should I alter basic strategy?

What kind of machine is it? multi-game with video poker and blackjack?

If it sounds too good to be true, its probably is.

That is such an insane rule "variation" that the Wiz doesn't include it in his list.
congrats on finding that machine.

I find it hard to believe that they will make such error.
But if this is the case, it is obvious that the game has substantial positive EV even without doing the math.

Guesstimate of EV:
Dealer gets 21 around 7.5% of the time.
Player mostly mimics delear when Upcard is 7 to A, 8/13 of the times (except say Doubles, splits and surrender)
Player stays a lot more on Stiffs for Upcards 2 to 6, 5/13 of the times.
So I would estimate that Player gets 21 about 75% as often as the dealer, ie 75% x 7.5% = 5.6%.
Say players wins 90% of these (other being pushes) that's 90% x 5,6% = 5%.
5% of the time player gets paid extra 50%.
That's 5% x 50% = 2,5%
So additional EV 2,5% less Standard EV -0,5%, EV = +2%.

So if I was you I will still be on that machine. (untill the figure out the mistake)


CHANGING BASIC Hit v Stand
Say Hitting a Stiff like 12 v 4.
Extra EV on Hit from rule = 1/13 x 50% X 90% = 3,5%.
So Hit EV increases by around 3,5%.
Any marginal Basic decisions with less than 3,5% between Hit and Stand (like 12 v 4) become Hit.
It should only be a few changes.

It DOES depend upon how many decks are used. All 21's pay 3/2 is prolly 0.8%. So the game is most likely +EV even with 8 decks, though not by much maybe +0.15%. The only changes to basic I would make is instead of Surrender (see charts), Hit.

Quote: 98Clubs

It DOES depend upon how many decks are used. All 21's pay 3/2 is prolly 0.8%. So the game is most likely +EV even with 8 decks, though not by much maybe +0.15%. The only changes to basic I would make is instead of Surrender (see charts), Hit.

There must be some other changes too. Here is how I would ballpark it (in my head / back of envelope calculations):

Ignoring removal, and ignoring the chance of a tie, any time you hit a stiff, you have a 1/13 chance of making an extra 1/2 bet. So, the value of hitting goes up by 1/26; about 3.8%. Now, it will be lower due to the chance of a tie. Without taking the time to do any real math, I'd call it 3.5%. So, on any play where the BS play is to stand but the EV of hitting is within 3.5% of standing, it becomes correct to hit. The wizard has the EVs of hitting vs standing for every decision in BJ appendix 9, so you can figure out which strategy changes to make. Off the top of my head, 12v4 and 13v2 become hits. I'm not sure if there are any more without checking the charts.

Oh, it may also be correct to skip some soft doubles and doubles on 9 or even 10, particularly against 7-A. I'm not sure without checking the numbers though.

If you double and get 21 do you get 3:2 on the doubled bet? If not, then it's worth checking whether hitting 11 v 7-T becomes better than doubling.

I'm going to assume six decks and no-resplitting aces. That said, I get player advantage of 3.16% of all winning 21s pay 3-2 and 3.98% if any 21 pays 3-2. Here is my infinite deck strategy for the latter way.



If this game is for real, I'd appreciate a donation for my trouble.

Either this was indeed a real thing and he realized how dumb it was to talk about in public or he made a mistake of some kind.

Thanks Wiz! I was hoping someone was going to look into it in more detail because I definitely was curious to know.

And looks like AxiomOfChoice did a decent estimate.

I gotta say that one of my pet peeves is when people start a thread and then never return to their own thread for discussion.

Quote: GWAE

I gotta say that one of my pet peeves is when people start a thread and then never return to their own thread for discussion.

I agree 100%.