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Last Updated: October 7, 2021

Straight 2 Flush


Straight 2 Flush is a blackjack side bet found on Dynasty electronic blackjack games. It pays based on the poker value of the player's first two cards and the dealer's up card.

Mathematically, the bet is the same thing as version 2 of 21+3.

I saw this bet at the Venetian Las Vegas on October 6, 2021.


Wins on the Straight 2 Flush bet are based on the poker value of the player's two initial cards and the dealer's up card. The bet pays 9 to 1 if the poker value of these three cards is a straight, flush, straight flush, or three of a kind. I presume a suited pair and singleton counts as a flush, for example suited 5-5-Q.

The following table shows my analysis for eight decks. It counts a suited three of a kind as a three of a kind. The lower right cell shows a house edge of 2.74%.

Eight Deck Analysis

Event Win Combinations Probability Return
Straight flush 9 24,576 0.002063 0.018568
Flush 9 700,928 0.058841 0.529572
Straight 9 368,640 0.030947 0.278519
Three of a kind 9 64,480 0.005413 0.048717
All other -1 10,753,536 0.902736 -0.902736
Total   11,912,160 1.000000 -0.027360

The next table summarizes the house edge for various numbers of decks.

House Edge

Decks House Edge
1 13.30%
2 7.26%
4 4.24%
6 3.24%
8 2.74%

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