You're dealt a pair of 5s. The dealer shows a 5. Split or play it as one hand? Basic strategy answers:
| Double ← | +0.5125 |
| Hit | +0.2563 |
| Split | +0.0599 |
| Stand | -0.1672 |
| You bust on the next card | 0.0% |
| Dealer 5 busts | 41.6% |
Double is not close: it beats Hit by 0.2563 per unit. Getting this one wrong costs $2.56 on a $10 bet, every single time. Across the 340 situations in this chart it ranks 46th by expected value — better than 294 of them, worse than 45. 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.
A pair of 5s is really a hard 10 — one of the best doubling totals in the game. Splitting would create two hands starting from 5, the worst possible start. Against a 5, play it as 10: double down and press your edge.