In blackjack, if you are dealt a pair of aces you have the option of splitting your cards into two new hands. If you take this option, you need to place a second bet, equal to your original stake, to cover the second hand. You are dealt one – and, in most casinos, only one – additional card on each split ace, you usually cannot double down after split and, if you are dealt another ace, you cannot split again.
According to basic blackjack strategy – which describes the mathematically correct way to play any hand – you should always split a pair of aces, regardless of the card the dealing is showing. A pair of aces technically makes a ‘soft’ total of 12 which, granted that tens and court cards make up 16/52, or 30.76%, of a standard deck of cards, is a difficult starting hand. Notwithstanding the fact that you need to double your stake, and therefore your risk, creating two hands in which the first card is worth 11 points is one of the strongest plays in blackjack; it is, in fact, one of the few moves that has a positive expectation against any dealer upcard.
Any ten or court card – or four of the 13 possibilities – will yield a total of 21, against which the best the dealer can do is push, while a 7, 8 or 9 – or another three of the 13 possibilities – will yield a total of 18 or better. The average winning hand in blackjack is 18.5 so, while there are also six possibilities whereby you can win only if the dealer busts, the attraction of splitting aces is clear to see.