Knowing whether or not to split a pair is an essential part of blackjack basic strategy. Sometimes the decision is simple, such as that you always split aces and never split fives. Other times, however, the strategy is more complex and depends on what cards the dealer shows. The most complex of all the pair splitting strategies is for a pair of nines.
If you have a pair of nines, what you do depends on the dealer’s up card. If the dealer is showing a two through a six, you should split your pair. If the dealer shows an eight or nine, you should also split your pair. If the dealer shows an ace, seven or 10, however, you should stand. This is the first pair where standing is an option in basic strategy. If you have a pair of nines, you should never hit. Now let’s look at this step by step.
Blackjack basic strategy takes into account that there are more cards with a value of 10 than any other value (4/13). For that reason, when taking a hit you are more likely to draw a 10 than anything else and the dealer is more likely to have a 10 in the hole than anything else.
For that reason, if the dealer shows a two through a six, he has a good chance of having a stiff hand (12-16). The dealer cannot stand on a stiff hand and since he has to hit, has a high likelihood of busting. If the dealer busts, you win no matter what cards you have, as long as you don’t bust as well. Therefore, by splitting the pair you are doubling your bet and stand to make twice as much money if the dealer busts, as the odds say is likely.
If the dealer shows an eight or nine, the odds say he is likely to have an 18 or 19. If he does and you stand on your 18, then you would either push or lose, respectively. Normally when you think the dealer has your cards beat you would take a hit, but doing so here is risky because you have an 18. With a hand that high, only 3 cards (ace, 2, 3) will help you and 10 cards (4, 5, 6, 7, 8, 9, 10, J, Q, K) will cause you to bust. Taking 3/13 odds is not a good idea. However, since your 18 is made of a pair of nines, you have the chance to improve your hand by splitting the pair. Once you split, you are starting each hand with a nine. Since you are more likely to receive a 10 card when taking a hit, you have a 4/13 chance of drawing a 19 and zero chance of busting (at least on the first hit).
If the dealer shows an ace or a 10, you are going to lose more often than not. An ace can stand for 11 or one point at the dealer’s discretion and can be used to make a blackjack. A 10 has a good chance of giving the dealer a 20, which can only be beaten by you drawing a 21. Therefore, since you are likely to lose if the dealer has either of those cards, you don’t want to put more money on the hand by splitting. You don’t want to hit to improve your hand because, as mentioned earlier, when hitting an 18 you have 10/13 odds of busting.
If the dealer shows a seven, he has a high probability of having a hand of 17. Since you already have 18, you have that hand beaten. For that reason, standing is the wise strategy. Next we will complete the pair-splitting guide by covering a pair of tens.