Second double on three cards (Triple)

Hello!
Sorry if this already been discussed on the forum, I cant find it. Maybe someone can help to calculate, or give a link. Effect to expected value rule that allows to make a second double(triple) after third card.

For example:
- The gambler has 5,4(9) make DOUBLE, and the comes out 2. Now gambler has 5,4,2(11), and he can do another double (amount of the initial bet. Total bet =3x initial bet).

Number of decks: 6
Dealer on a soft 17: Stands
Double after a split: Yes
Resplit to: 4 hand
Player can resplit aces: No
Player can hit split aces: No
Player loses only original bet against dealer BJ: No
Surrender: Standart
Blackjack pays: 3 to 2

What advantage will get the Gambler if he always makes the optimal decisions?

This is a common rule variation in Spanish 21, where it is worth 0.34%. It should be worth even more in blackjack. If forced to make an estimate, I'll go with 0.4%.

Quote: Wizard

This is a common rule variation in Spanish 21, where it is worth 0.34%. It should be worth even more in blackjack. If forced to make an estimate, I'll go with 0.4%.
link to original post

In Spanish the second double would be 2 units for a total of 4 units. The third redouble in Spanish is 4 units for a total of 8.

Hello,

My first post on Wizard of Vegas. I just want to say what Fantastic site this is! I don't know how many times I've found useful information on games because of your analysis or the comments of members. Truly, thank you for sharing these insights and revelations over the years. Of course, my favourite part is always reading "is this countable?" "Shut up Wiz!" haha.. :-D

Just to add to what's already been said. Stamford Wong's book professional blackjack has a short section on re-doubling in Blackjack, although presumably this would be a total 4 units instead of 3 having doubled and then redoubled. He states: redoubling is worth 0.4% with No DAS and 0.6% with doubling after splits allowed. Variance is 1.4 instead of 1.3 and 1.43 if doubling is allowed after splitting.

His benchmark rules in the book were:
Six Decks
S17
Double down allowed on any first two cards but not after splitting
Resplits allowed up to four hands,
Split aces receive one card each and cannot be resplit
No surrender
Naturals pays 3:2


Cheers

Mac

Quote: Wizard

This is a common rule variation in Spanish 21, where it is worth 0.34%. It should be worth even more in blackjack. If forced to make an estimate, I'll go with 0.4%.
link to original post

Yes. I get a difference of 0.4363% between the base blackjack game and the game with the triple down rule. (I used the infinite-deck model instead of 6 decks.)

The only stiff re-doubles are 12 vs 7-8 and 13 vs 7.

I get these soft doubles: 13-18 vs 3-6 and 13-14 vs 2.

My hard doubles are:
10-11 vs 2-9
9 vs 2-8
8 vs 2-6
6-7 vs 5-6
4-5 vs 6
However, split 2s and 3s instead of doubling down.

The only change in splitting is don't split 4s.

Quote: Mac1

I just want to say what Fantastic site this is! I don't know how many times I've found useful information on games because of your analysis or the comments of members. Truly, thank you for sharing these insights and revelations over the years. Of course, my favourite part is always reading "is this countable?" "Shut up Wiz!" haha.. :-D
link to original post

Thank you and you're welcome! Welcome to the forum.

Quote: ChesterDog

Quote: Wizard

This is a common rule variation in Spanish 21, where it is worth 0.34%. It should be worth even more in blackjack. If forced to make an estimate, I'll go with 0.4%.
link to original post

Yes. I get a difference of 0.4363% between the base blackjack game and the game with the triple down rule. (I used the infinite-deck model instead of 6 decks.)

The only stiff re-doubles are 12 vs 7-8 and 13 vs 7.

I get these soft doubles: 13-18 vs 3-6 and 13-14 vs 2.

My hard doubles are:
10-11 vs 2-9
9 vs 2-8
8 vs 2-6
6-7 vs 5-6
4-5 vs 6
However, split 2s and 3s instead of doubling down.

The only change in splitting is don't split 4s.
link to original post

Chester are your numbers for betting 4x original bet or 3x ?

Quote: Hunterhill

...
Chester are your numbers for betting 4x original bet or 3x ?
link to original post

3x.

For example, suppose the player bets $10. The player is dealt a six and a two, and he doubles-down by putting up another $10. His double-down card is three, so he puts up a third $10 hoping to get a face card.