Expected value of 1.5 BJ or double down 10+A
But it makes me wonder... just what is the expected value of doubling down an initial $5 to try to win $10 vs the guaranteed $7.50?
The rules are 3:2 single deck, double down 10 or 11, no double after split, no surrender.
The old rules in the UK didn't prohibit doubling a Blackjack, but nowadays you're not allowed to. Also some casinos have a house rule that do not allow you to hot or double soft 21 (it can happen from splitting 10s as well).
Quote: charliepatrickAlso some casinos have a house rule that do not allow you to hot or double soft 21 (it can happen from splitting 10s as well).
When a game has an automatic winner rule if you have x cards, if you're just one card short you'd legitimately want to hit a soft 21 (standing leaves open the possibility of the dealer pushing your hand).
Usually when it's doubling 10 or 11 only they specify it must be a hard 10 or 11. A lot of states also don't let you double on blackjack, for the players safety. There is a point in time in the count where you double blackjacks... but I think I'd have to look it up =P.Quote: KevinAA...double down 10 or 11...
Quote: KevinAAA player today had a blackjack, and he asked me if he could down down, i.e. count the ace as 1, plus the 10, is 11, so double the bet that hoping for a 10, for a total of 21, beat the dealer, and win $10 instead of $7.50 on a $5 bet. I said "you can do that". His friend said it was a stupid idea, and he took the BJ win instead of doubling down.
But it makes me wonder... just what is the expected value of doubling down an initial $5 to try to win $10 vs the guaranteed $7.50?
The rules are 3:2 single deck, double down 10 or 11, no double after split, no surrender.
A very rough estimate.
Well, if you always do it...4 of 13 cards you get when you hit are 10s. So +$80 if you don't push the dealer. 1 is a 9. Win 80% of those, so+ $16. On 8s, +12. On 7s, +8. 6s, +4. A-5, -50. +$70 so far.
x 1.28 for dealer bust. $89.60.
Vs 12.50 x 13 = $162.50.
Without accounting for pushes or dealer blackjacks, which would make the disparity larger. (I'm assuming dealer peeks before it gets to you.)
Maybe in very limited/rare situations, in high + counts with dealer 3-6, it's worth doubling, but losing that guaranteed 3:2 pay in general seems very expensive to me. Check the counting indexes for exceptions where you would, I think. As BS, no.
try here (this might be what you are after)Quote: KevinAABut it makes me wonder... just what is the expected value of doubling down an initial $5 to try to win $10 vs the guaranteed $7.50?
http://www.bjstrat.net/cgi-bin/cdca.cgi
Conditioned on no dealer BJ where applicable was unchecked
that website has a windows program, but it looks to have many errors in it at times
I like this as it shows the probabilities calculated
No, there is no count where you would double down on a blackjack. There is a count where you want to double down on a soft 21, say after splitting tens and getting an ace, and that starts at +9 for vs 5 and 6.
Quote: BlackjackGuy123
No, there is no count where you would double down on a blackjack.
Why would you not double down if the count of ten valued cards equaled the number of cards remaining in the deck?
I guess if you are keeping a separate 10 count. But if you were hi lo counting and doubled and got an Ace that would suck.Quote: DRichWhy would you not double down if the count of ten valued cards equaled the number of cards remaining in the deck?
Quote: BlackjackGuy123Pretty obvious the EV is the same as doubling 11 v whatever the dealer's card is. See wizard of vegas expected result of every play table.
BlackjackGuy123,
Although substantially correct, your answer is slightly in error due to the effect of removal: when you DD on, say, 6-5, you still have all the ten-valued cards available; when you DD on A-10, the available cards are short one ten.
Hope this helps!
Dog Hand
1Quote: DogHandBlackjackGuy123,
Although substantially correct, your answer is slightly in error due to the effect of removal: when you DD on, say, 6-5, you still have all the ten-valued cards available; when you DD on A-10, the available cards are short one ten.
Hope this helps!
Dog Hand
They are also short an Ace, which everyone knows is the card you are most likely to get when you double an 11, especially with a larger than average bet on the line.
Quote: DRichWhy would you not double down if the count of ten valued cards equaled the number of cards remaining in the deck?
The first card is discarded, so there is no way to guarantee that all remaining cards are tens, even if the dealer counted the cards left in the deck and told you "there are 12 cards left" and the running count is +12 and all four aces are gone.
