You're dealt a pair of aces. The dealer shows a 10. Split or play it as one hand? Basic strategy answers:
| Split ← | +0.1797 |
| Hit | -0.0700 |
| Double | -0.5140 |
| Stand | -0.5404 |
| You bust on the next card | 0.0% |
| Dealer 10 busts | 23.0% |
Split is not close: it beats Hit by 0.2497 per unit. Getting this one wrong costs $2.50 on a $10 bet, every single time. Across the 340 situations in this chart it ranks 108th by expected value — better than 232 of them, worse than 107. Expected value is per unit staked, computed for multi-deck, dealer stands on soft 17, double after split allowed. The model and the code are published as data.
Two aces are worth 12 together — a terrible total. Split, and each ace becomes the start of a hand worth ~52% of a blackjack. Splitting aces is the single most profitable move in the game, against any dealer card, including a 10.