This article discusses some blackjack bets.
You bet on whether the total on your first two cards will be over thirteen or under thirteen. Aces count one. Thirteen loses. The casino edge on the "over" is 6.8% or more, with the exact amount depending on the number of decks. The "under" bet is worse than the "over" , giving the casino more than 10%.
You bet on the color of the dealer's first card. If the dealer's first card is a deuce of the color you bet, you have a push; that gives the casino its edge: 3.8%.
3. Multiple Action.
In multiple-action blackjack, you may make up to three bets, each of which has action against a different dealer hand.
Your hand is the same for all three of your bets. The dealer's first card is the same for all three of your bets. The dealer's hand is finished out once, and then the first bet for each player is settled. Then all dealer cards are discarded except the first one, and the dealer's hand is played out again. The result of this hand is used to settle each player's second bet. Then once again all dealer cards except the first one are discarded, the hand is played out again, and each player's third bet is settled.
You should use the same playing strategy at multiple action as at regular blackjack. The fact that the dealer will be playing out a hand three times does not affect basic strategy.
Even if you know you should hit your hand, sometimes you will be tempted to stand. The excitement of remaining alive to play against the dealer is sufficiently strong an incentive to induce some players to intentionally go against basic strategy. That is a mistake.
From a risk standpoint, multiple action is slightly more risky than regular blackjack. Of course one bet of multiple action has the same risk as one hand of regular blackjack. However, making two bets on one hand at multiple action is slightly more risky than playing two simultaneous hands of regular blackjack. Likewise, playing three hands of multiple action is slightly more risky than playing three simultaneous hands of regular blackjack.
Your optimal bet size as a proportion of your bankroll depends on the number of simultaneous bets you are making. For one bet, it is your edge divided by the variance of possible outcomes. For each of two simultaneous bets (or two simultaneous hands), it is your edge divided by the sum of the variance and the covariance. For each of three simultaneous bets or hands, it is your edge divided by the sum of the variance plus twice the covariance. Typically the variance is around 1.3 and the covariance is around 0.5.
Simulation shows that the covariance between multiple-action bets is about 10% higher than the covariance between simultaneous hands in a regular blackjack game. Your optimal bet size if you are making two bets at multiple action is 97% of your optimal bet size if you were playing two simultaneous hands at regular blackjack. Your optimal bet size if you are making three bets at multiple action is 96% of your optimal bet size if you were playing three simultaneous hands at regular blackjack.
An easy-to-remember rule is 14/16. For two hands, bet a total of 140% of what you would bet on one hand (70% per hand). For three hands, bet a total of 160% of what you would bet on one hand (53% per hand).
4. Royal Match.
Royal Match is a side bet at blackjack - you are wagering that your first two cards will be of the same suit. If your first two cards are K-Q of the same suit, you win extra. If your first two cards are K-Q of the same suit, you win ten to one on your "royal" bet. At single deck, you will be dealt K-Q of the same suit one hand out of 331.5. If your first two cards are of the same suit but not K-Q, you win three to one on your royal bet. The casino edge is 3.8%.
5. Bust Box.
Bust box is a side bet that you will bust. The maximum you are allowed to bet in the bust box is half your original bet. After you make the bust-box bet, you get one and only one more card. If you bust, the bust-box bet wins even money. If you do not bust, the bust-box bet loses.
Each time the bust-box bet is recommended, you gain 3% to 4% of an original bet (6% to 8% of the bust-box bet). Overall, the value to you of being able to make bust-box bets is 0.2% of your original bet.