Blackjack table

Hard 10 against a dealer ten: basic strategy says hit, since doubling is only profitable against dealer 2-9 and standing on 10 has no chance to improve.

Hard 17 vs dealer 10 — standing is correct; hitting risks busting with little gain.

A pair of 5s is a hard 10 — never split 5s; doubling against a dealer 5 upcard is the basic-strategy play with strong expected value.

Hard 15 against a dealer 6 is a basic-strategy stand; the dealer's high bust probability makes hitting unnecessary and doubling too risky.

Soft 19 vs dealer 3 under S17 rules is a stand per basic strategy; doubling is only correct against 5-6 in S17 games.

A pair of 8s is a hard 16, the worst total in blackjack; basic strategy is to split 8s against every dealer upcard, and a dealer 3 is weak, so two hands starting from 8 each have far better expected value than hitting or standing on 16.

Hard 15 against a dealer 3 upcard is a basic-strategy stand; the dealer has a high bust probability and hitting risks busting. Doubling hard 15 vs 3 is not profitable.

Soft 19 is already a strong made hand, and with dealer standing on soft 17 the correct play vs a 3 is to stand; doubling soft 19 vs 3 is only considered vs 6 in H17 games and is worse here.

Hard 20 is a near-made hand; standing maximizes expected value against a dealer 2 upcard. Hitting or doubling risks ruin for negligible gain.

Hard 15 against a dealer 2 is a basic-strategy stand; the dealer's low upcard busts often enough that hitting risks breaking more than it gains.

Hard 19 is a strong made hand; standing is optimal against a dealer 7. Hitting or doubling would risk a near-certain win.

Hard 20 is the second-strongest total; standing wins against most dealer outcomes and any hit risks an almost certain loss of EV.

Hard 10 against a dealer 9 is a standard double per basic strategy; the expected value of doubling exceeds hitting since the dealer has a high bust rate and I can only improve to a strong hand with one card.

Hard 20 vs dealer 3 is a lock; standing wins far more than any alternative.

Hard 19 is a strong made hand; standing is optimal against any dealer upcard, and doubling would risk ruining a near-winning total.

Hard 15 against a dealer 10 (King) is a basic-strategy hit; standing loses about 78% of the time, while taking one card improves expected value. Surrender is unavailable, so hitting is optimal.

Hard 17 vs dealer King is a clear stand per basic strategy; hitting risks busting with no upside since 17 already beats most dealer outcomes.

Hard 16 against a dealer 10 is a basic-strategy hit; standing only wins if the dealer busts (~21%), while drawing a small card improves the hand often enough to lower expected loss.

Hard 18 vs dealer 8 is a stand per basic strategy; hitting risks busting for minimal gain.

Hard 14 against a dealer Ace; since the dealer peeked and did not have blackjack, basic strategy calls for hitting rather than standing or splitting sevens.

Hard 20 is a near-made hand; standing wins against a dealer 2 in the vast majority of cases. Doubling or splitting tens would only reduce expected value.