I read this article on Vegas Chatter and saw a comment regarding sticking it to the casinos on 6/5 Blackjack by treating Blackjacks against a dealer bust card (4,5,6) as an 11 and doubling down. See the link to the story below. http://www.vegaschatter.com/story/2015/5/7/155255/2361/vegas-travel/A+Tale+of+Two+Blackjack+Payouts+at+Downtown+Grand Now, let me preface this by saying that I will not normally play 6/5 BJ as a matter of principle, but I will sometimes play 6/5 BJ at low limits or party pits with friends on a tight budget for fun. I know I shouldn't do this because it perpetuates the 6/5 BJ, but sometimes I just want to enjoy the time at the table with my friends. With that being said, from a mathematical perspective, would it make sense to double a blackjack against a dealer 4,5, or 6 at a 6/5 BJ table?
This is not a good way of beating 6:5 BJ. Your expected return for doubling 11 vs a 4-6 is between 0.566 and 0.667 units. Your expected return for taking the natural payout is 1.2 units. Which would you take?
At $10 a hand 100 naturals will pay you $2,200 (including original bet). Profit of $1200. 100 double downs on a 11 vs 4-6 should pay around $1800 (including original bet). Profit around $600.
Except you forgot to account for the fact that you win 100% of the time on the natural blackjack and only about 55-65% of the time on the doubles which leaves you with about $1200 profit again and MUCH more volatility. Take the 6/5 and run if you are going to play with those poor odds.
Its a stupid move to give up a winning hand to put more money out there (your double up) and have only a chance at a win. Numbers-wise: If the dealer has a 5 or 6 there is only about a 42% chance of the dealer busting, 57% chance they make 17 or better... for the player there is a 46% chance you will be dealt an A, 2, 3, 4, 5 or 6 (including the 6 because it makes 17, which is lowest limit of the dealer beating or pushing) which will not give you that great a hand.
I agree with everyone here. When I saw that comment on the article I thought that doesn't make any sense, but I thought maybe I was missing something. I very rarely play 6/5 BJ, so it doesn't really matter, but you all have confirmed that a 6/5 guaranteed win is still better than a better than average chance for a 1/1 win for twice the risk.
I probably know the answer, but what if you only doubled against a dealer "6", but took the natural against a dealer "4" or "5"??
Nope. Still not even close. Though I've always thought that it's a good ploy to bring attention to the lame payout. Many new or casual players don't even know they're being short changed and refusing the automatic win in favor of a double down always draws the attention of the whole table and will almost always cause people to ask what you're doing. But if you're not willing to give up EV in order to educate others, never double down a "soft 21".
When I saw this thread I murmured to myself that the first reply would be not to play 6:5. Well done Top on the "War Games" quote. Nice analysis on the numbers sigsev. Between the two of you you nailed it.
Yes they do allow you to do that - casino should love it actually. I once played with a guy who did it at a 3:2 table. Same guy told me I was wrong when I hit a 12 to a dealer 2.