Guarantee 20

About a year ago, a rule called "Guarantee 20" started showing up on blackjack tables. I've taken little note of the option -- it's not widespread, and it's not to the players' advantage to take the guarantee offered.

But a couple of things have happened lately. Trump Casino in Gary has joined Empress Hammond in offering the rule, which basically allows a player dealt a two-card 20 to accept winnings equal to 50 percent of his bet instead of taking a chance on winning the whole thing.

It's become a hot topic for me online lately, with two persistent backers of the guarantee engaging me in an e-mail debate.

Here's the way it works. The players' cards are dealt face up, while both of the first two dealer cards are dealt face down. Players with two-card 20s are offered a guarantee, and if they accept they are guaranteed a win of half their wager. There is one exception: If the dealer has blackjack, players who take the guarantee get a bonus win of 150 percent of their wagers.

A player with a $10 bet who takes the guarantee would win $5 even if the dealer has 20 or a multi-card 21. If the dealer has a blackjack, then the $10 bet brings $15 in winnings.

The wary player might say, "I might like that guarantee sometimes, but I don't want it if the dealer's up card would have been a 5 or a 6. I'm likely to win most of those hands. Why would I settle for half?"

For those players, there's a "second chance" feature, in which they get another shot at the guarantee if the dealer then turns a 10-value card as his up card, and if the dealer does not have a blackjack.

Note the second part of that second chance rule. Second chance players get no bonus on dealer blackjacks. They lose their bets.

My correspondents who have been touting Guarantee 20 point to one basic strength: Blackjack players who take the guarantee need never again know the frustration of being dealt a 20 only to lose to a 21 or push against a dealer's 20.

"Where else in gambling will you ever find a sure winner?" they ask. "Why gamble on 20 when the guarantee is available? Take the guarantee, then gamble on the next hand."

Problem is, the player who takes the guarantee is gambling. He or she is giving up half the potential winnings on a good hand, gambling that the dealer is going to wind up with a hand that's as good or better.

Most of the time, that's not going to happen.

Let's look at the first part of the guarantee. The percentages very slightly according to the number of decks in play and whether the dealer hits soft 17, so let's take the game available in northwest Indiana.

Dealt a 20 in an eight-deck game in which the dealer stands on all 17s, the player is going to win 70 percent of all hands, lose to 21s 12 percent of the time and tie dealer 20s on 17 percent of hands. For every $100 the player wagers, the average win will be $58.06.

What if the player accepts the guarantee? The player will win half a bet on 95.3 percent of hands, and win the 150 percent bonus payoff on the 4.7 percent of the time the dealer turns up a blackjack. For every $100 the player wagers, the average win will be $54.71.

Check out those numbers. The tradeoff for the comfort of winning on every 20 is that you spot the house an extra $3.35 for every $ 100 you wager on those hands. Ouch.

What about the second chance option? You're starting off knowing the dealer has a 10 up, so that must be better for the player, right?

Wrong. It's worse.

It would be better if we had the shot at the bonus on a dealer's blackjack. But we don't. We lose if the dealer has an Ace go with that 10.

So the second chance comes into play only when we have a 20 and the dealer has a 10 up without having an Ace down. The dealer will tie us by making 20 on 36.6 percent of hands, and beat us with a 21 of three or more cards 3.8 percent of the time. We win 59.6 percent of hands.

For every $100 we wager in this situation in an eight-deck game, we will win $55.76 if we stand on our 20s, but win only $50 if we take the second-chance guarantee. The house edge is 5.76 percent.

The basic strategy for blackjack with Guarantee is simple. Stand on your 20s, and never take the guarantee.

My correspondents have tried to downplay the math, pointing out that every casino game has a house edge.

My answer: Guarantee 20 is not a game in itself. It is an optional rule, one that increases the house edge on blackjack.

Yes, blackjack carries a house edge against all but the best card counters. Blackjack with Guarantee 20 has a higher house edge. I recommend the game with the lower house edge.

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