Those Double Nines

19 November 2023

By John Grochowski

QUESTION: If I have a pair of 9s in blackjack, basic strategy says I should split them when the dealer has an 8, but stand on my 18 when the dealer has a 7. That seems backward to me, risking a second bet when the dealer has a higher starting card.

ANSWER: You have to consider the effect of more than 30 percent of cards in the deck having values of 10. If the dealer has a 10 or face down, his 7 becomes a 17. Your 18 wins, so it's better not to break it up by splitting the 9s. If the dealer has an 8 down, and 10 turns it into 18, so your 18 would push. You gain by splitting the 9s and hoping you'll land a 10 or two to beat that 18.

At wizardofodds.com, Michael Shackelford has a chart detailing percentages of dealer finishing hands for each face up card. In a six-deck game in which the dealer hits soft 17, a dealer finishes at 17 on 36.9 percent of hands that start with 7, but only 12.9 percent of hands that start with 8. In comparison, the dealer finishes at 18 on only 13.8 percent of hands that start with 7, but 36.0 percent of those that start with 8.

That leads to the strategy split. If you have 9-9 and the dealer has 7 up, you win an average of 40.0 cents per dollar wagered if you stand. If you split, your win decreases to 36.4 cents per dollar of your original wager. You risk more money, but you win less. So basic strategy tells you to stand.

But if the dealer has 8 up, standing brings a profit of only 10.1 cents per dollar, a steep drop from the situation with 7 up. By splitting, you increase the average profit to 23.1 cents per dollar of the original wager. That makes it an easy call to split 9-9 against 8.

Basic strategy calls for splitting 9-9 against every dealer up card except 7s, 10 values and Aces. By standing against 7s, you're playing offense, moving to win more money. Against 10s and Aces, you're playing defense because the average result for 9-9 is a loss no matter which play you make. Better to avoid the split and putting more money at risk in a losing situation.

Similarly, most 9-9 splits put you on the offensive to maximize profits. But with 9-9 against 9, you're playing defense. Average loss for hitting in that situation is 18.5 cents per dollar wagered. Splitting reduces the loss to 8.1 cents per dollar of your original wager. You can hope for a win while understanding that sometimes you'll lose twice your bet, but the average effect is to lose less and conserve bankroll.

QUESTION: My friend returned from a trip to Europe and said he skipped playing blackjack in casino because the dealer didn't take a hole card. The dealer just got one card face up and took the rest of his cards after players finished. Why does this make a difference? The dealer doesn't show his down card until after players finish anyway.

ANSWER: A dealer who has no hole card can't check for blackjack when the up card is an Ace or 10 value. Players double down or split without knowing if the dealer has blackjack, and they lose all split and double bets if the dealer then completes a blackjack. They lose bets they wouldn't have made if a dealer blackjack stopped the hand. That adds .11 percent to the house edge.