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# Basic strategy does not assume the dealer has a ten

26 July 2011

It was time for a get-together with my old blackjack-playing buddy Bob. I've mentioned him before. We'll talk about kids — and in his case, grandkids — baseball and life in general, just like normal people. But at some point, a blackjack issue always pops up.

"You know me," he said. "I've played basic strategy for about a hundred years, and have picked up some wrinkles beyond the basics. But a guy at the office has been trying to convince me it's all wrong."

I asked what was supposed to be all wrong.

"He said basic strategy assumes the dealer has a 10 face down, and that if the dealer has a 5 under a 6, then that it's a far different situation than if the dealer has a 10 down for a 15 total.

"I told him that OF COURSE that's a different situation, but there's nothing players can do about it. You can't base a strategy on information you don't have. All you can do is the best you can given the cards on the table."

Or given all the cards that have been played since the last shuffle, if you're counting cards.

"Sure," Bob continued. "But I didn't want to kick the conversation up another level. Keep it basic, you know."

I grinned, and mentioned that basic strategy doesn't assume a 10 value face down at all. The whole premise of Bob's co-worker's objection is wrong. Basic strategy assumes a normal proportion of cards in the remaining deck.

All the possibilities are considered. The chances that the dealer will have a 10-value face down were calculated. So were the chances that the down card will be a 4, 5 or any other card. Basic strategy is the play that will give you the best chances of winning given an average proportion of cards to be played.

There isn't always an average proportion of cards in the remaining deck. That's why card counters veer away from basic strategy. For example, when you have 12 and the dealer has a 2 face up, basic strategy is to hit. But if the true count in a Hi-Lo system reaches plus-3 — meaning there are three more high cards than low cards per deck remaining to be played — a counter will stand on the 12 instead.

Changes like that are a matter of using all the information available to a player who really wants to work at it. For most, basic strategy is the way to go, and it by no means assumes a 10 down.

"I told him something like that," Bob said. "I told him basic strategy is a best average play with everything considered, and he insisted it didn't work if the dealer didn't have a 10 down. Nothing I could say would convince him.

"I tried to give him the examples of 12 against 2 and 12 against 3, only I didn't go into the card counting thing and changes with the count. I mentioned that basic strategy says to hit those hands, and that I didn't thing it would if it was assuming the dealer had 10s down for 12 or 13. He just shrugged that off."

I told Bob he could try giving his co-worker a couple of more radical examples. If basic strategy really assumed a 10 face down, then some of the plays would be radically different. If the dealer had a 9 face up and you assumed the dealer had a 10 face down, would you stand on 17 or 18? Those hands can't beat a dealer's 19.

But basic strategy doesn't assume a 10 face down. It assumes that nearly 70% of the time, the dealer won't have a 10 down. It assumes that roughly 38% of the time, the dealer will have a 3, 4, 5, 6 or 7 down that would combine with a 9 to give the dealer a hand that can be busted in one-card hit.

It takes into account all those possibilities and more, and tells us not to hit 18 against a 9, as we would if the dealer always had 10 down.

"Oh, I can't wait to try that one out at the office," Bob said with a smile. "A little extra ammunition for the next argument."

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John Grochowski

John Grochowski is the best-selling author of The Craps Answer Book, The Slot Machine Answer Book and The Video Poker Answer Book. His weekly column is syndicated to newspapers and Web sites, and he contributes to many of the major magazines and newspapers in the gaming field, including Midwest Gaming and Travel, Slot Manager, Casino Journal, Strictly Slots and Casino Player.

Listen to John Grochowski's "Casino Answer Man" tips Tuesday through Friday at 5:18 p.m. on WLS-AM (890) in Chicago. Look for John Grochowski on Facebook and Twitter @GrochowskiJ.

#### Books by John Grochowski:

John Grochowski
John Grochowski is the best-selling author of The Craps Answer Book, The Slot Machine Answer Book and The Video Poker Answer Book. His weekly column is syndicated to newspapers and Web sites, and he contributes to many of the major magazines and newspapers in the gaming field, including Midwest Gaming and Travel, Slot Manager, Casino Journal, Strictly Slots and Casino Player.

Listen to John Grochowski's "Casino Answer Man" tips Tuesday through Friday at 5:18 p.m. on WLS-AM (890) in Chicago. Look for John Grochowski on Facebook and Twitter @GrochowskiJ.