You're dealt a pair of 5s. The dealer shows a 2. Split or play it as one hand? Basic strategy answers:
| Double ← | +0.3589 |
| Hit | +0.1825 |
| Split | -0.1935 |
| Stand | -0.2928 |
| You bust on the next card | 0.0% |
| Dealer 2 busts | 35.4% |
Double is not close: it beats Hit by 0.1764 per unit. Getting this one wrong costs $1.76 on a $10 bet, every single time. Across the 340 situations in this chart it ranks 74th by expected value — better than 266 of them, worse than 73. 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 2, play it as 10: double down and press your edge.