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Blackjack table

Blackjack · 20 rounds · Sep 25, 2026, 8:38 PM UTC

Round 20

Dealer

Round 20 result · Dealer 21

Claude Opus 5.5 Loss -10
1

Claude Opus 5.5

940

 

Hand 1 · 15 · bet 10

Loss -10

219 / 219

Action timeline

Model's stated reason

Basic strategy for a hard 12 against a dealer 10 is to hit. Standing on 12 loses more often against a strong upcard.

Model's stated reason

Basic strategy is to stand on a hard 17 against any dealer upcard. Hitting against the dealer's 10 would bust too often to be worth it.

Model's stated reason

A hard 5 against a dealer 3 is always a hit under basic strategy. Doubling is too weak here and standing can't win often enough.

Model's stated reason

Basic strategy with a hard 15 against a dealer 3 is to stand, since the dealer has a high chance of busting and hitting risks busting our own hand.

Model's stated reason

Basic strategy for a 6-deck S17 game says to hit hard 9 against a dealer 8, since doubling is only correct against 3 through 6.

Model's stated reason

Soft 20 against a dealer 8 is a clear stand under basic strategy. It beats most of the dealer's likely final totals.

Model's stated reason

Basic strategy for a hard 14 against a dealer 4 is to stand. The dealer has a high bust chance, while hitting risks busting.

Model's stated reason

Basic strategy says to hit a hard 13 against a dealer 10 (no surrender available). Standing loses more often, because the dealer is likely to make 17 or better.

Model's stated reason

Basic strategy for a hard 14 against a dealer Ace (S17, surrender unavailable) is to hit. The dealer has already peeked and has no blackjack, so their Ace is strong.

Model's stated reason

Under basic strategy, a pair of 4s against a dealer 10 should be played as a hard 8 and hit. Splitting or doubling against a strong upcard loses more on average.

Model's stated reason

Basic strategy says to hit a hard 13 against a dealer 10. The dealer is likely to make 17 or better, so standing loses more often than the risk of busting.

Model's stated reason

Basic strategy says to hit a hard 8 against a dealer 8, since doubling on 8 only pays off against a dealer 5 or 6.

Model's stated reason

Basic strategy says to hit a hard 15 against a dealer 8. Standing leaves the dealer too likely to make a pat hand.

Model's stated reason

Basic strategy says hit a hard 12 against a dealer 2 in a 6-deck S17 game. The dealer's 2 is not weak enough to justify standing.

Model's stated reason

Hard 14 against a dealer 2 is a standard stand in basic strategy because the dealer has a real chance to bust. Hitting risks busting for little gain.

Model's stated reason

Basic strategy says to hit a hard 14 against a dealer 8, because standing loses more often than risking a bust.

Model's stated reason

Basic strategy says to hit a hard 15 against a dealer 8. The dealer is likely to reach 17 or better, so standing on 15 loses more often than hitting does.

Model's stated reason

A hard 19 against a dealer 8 is a clear stand under basic strategy. Hitting risks busting, and 19 already beats the dealer's most likely final total of 18.

Model's stated reason

Basic strategy says to hit a hard 8 against a dealer 10; standing or doubling would both lose value.

Model's stated reason

Basic strategy says to hit a hard 13 against a dealer 10, since standing on 13 loses more often than risking a bust.

Model's stated reason

A hard 17 against a dealer 10 is a stand in basic strategy, since hitting busts too often. Standing loses less than hitting.

Model's stated reason

Basic strategy says to hit hard 14 against a dealer 10, since standing on a stiff total loses more often. Surrender isn't available here.

Model's stated reason

Basic strategy says stand on a hard 17 against a dealer 10. Hitting would bust too often to be worth it.

Model's stated reason

Hard 11 against a dealer 5 is a textbook double under basic strategy. The dealer's weak upcard raises their bust chance, so putting more money in maximizes expected value.

Model's stated reason

A pair of 5s should be played as a hard 10, and basic strategy doubles hard 10 against a dealer 7. Doubling beats both hitting and splitting here.

Model's stated reason

Basic strategy says to hit a hard 13 against a dealer 10. With surrender unavailable, hitting has a better expected value than standing.

Model's stated reason

Hard 17 against a dealer 3 is a stand in basic strategy. Any hit risks busting on most cards, while the dealer has to draw from a weak upcard.

Model's stated reason

Basic strategy says to stand on a hard 14 against a dealer 6. The dealer has a high bust chance, so there's no reason to risk busting by hitting.

Model's stated reason

Basic strategy says hit a hard 12 against a dealer 7, because the dealer is likely to make a strong total.

Stated reasons appear after the comparison block is revealed. They are model-submitted text, not verified reasoning.

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Result

Session result: -60 chips over 20 rounds

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