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Posts Tagged ‘Rule of Eight’

Your Blackjack Hand: A-4 or A-5

Posted by blackjackguru on June 21, 2009

6 decks, S17, DAS, No Surrender, Peek
Estimated casino edge for these rules: 0.44 %
Dealer Upcard
Your
Hand
2 3 4 5 6 7 8 9 10 A
A,4 or A,5 H H D D D H H H H H

This is called soft 15 or soft 16. Standing is not the right thing to do because you cannot push with these hands and you can only win if the dealer busts, which happens just over 28% of the time. You should hit most soft hands, including these ones, but keep a lookout for the chances to double down, which are:

Dealer upcard 4: Double down your A-4 and A-5, your long run advantage is about 6% of total wagers placed. Note that doubling here is only slightly better than hitting. Think of the dealer upcard of 4 as the starting point of confident soft doubles.

Dealer upcard 5: Double down your A-4 and A-5, your long run advantage is about 13% of total wagers placed. Had you just hit your long run advantage is significantly lower, about 8% – 9%.

Dealer upcard 6: Double down your A-4 and A-5, your long run advantage is about 18% of total wagers placed. Just hitting these hands yields less, about 10% – 11%. This should intuitively be the best dealer upcard to double against, and it is.

Common Loser Mistakes:

  • Doubling down A-4 and A-5 against Dealer upcard 3. Soft doubling is the most confusing plays to remember, and a lot of losers get this one wrong. Remember, the dealer’s 3 is deadly, only less so than the dealer’s 2. The Advantage Player will just hit A-4 and A-5 against the dealer 3, because she knows her chances are thin, less than 1 to 3%. She knows if she doubles her long run expectation becomes negative, losing almost 1% of total wagers placed.

Did You Know..?

One way to remember the soft double down strategies is to think of “the rule of 8” against dealer’s stiff upcards of 4, 5, 6. If you take the dealer’s upcard plus the card you have next to your ace, and the total is 8 or higher, you can double. Examples:

  • Ace-2 vs dealer 6 = “my 2 plus dealer’s 6 equals 8…I can double down”
  • Ace-3 vs dealer 5 = “my 3 plus dealer’s 5 equals 8…I can double down”
  • Ace-4 vs dealer 4 = “my 4 plus dealer’s 4 equals 8…I can double down”
  • Ace-5 vs dealer 3 = “the dealer 3 is not a good bust card, I learned that from Blackjackguru. I should just hit”

A fine point here: the above Rule of Eight fails to capture the legitimate double down of A-2 vs dealer 5. But recall that we learned in a prior lesson that doubling down your A-2 vs dealer 5 is only slightly better than hitting. Hitting is also a positive long run decision, gaining about 13.7%, compared to doubling down which gains 14%. So remember it and win more, or forget it and win a bit less.

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