Making Money At Black Jack (well not exactly)

UPDATE: This is a post from a couple of weeks ago. My son Jason questioned me about it. We even set down and simulated it at the kitchen table.

A little while later he sent me a text with the following link. Seems that when I first thought about it, I was a couple of centuries too late. It even has name, The Martindale System – named that in 1939.

Oh well, I should have looked it up on

Wikipedia back in the 80s. Wait, we didn’t have such a thing, now did we.

I was sitting around one day and had become intrigued with blackjack. I enjoyed going to Las Vegas and playing or just about anywhere else I could get involved in a game . I wasn’t too bad but I wasn’t able to retire off my winnings either.

It came to me one day that if I took $5000 to Las Vegas and played $5 blackjack that I could make a good living doing so.

Most people think when you start winning you should raise your bet because you’re on a hot streak. My mind didn’t work that way. I thought if you played a hand and won, you made $5.

However if you lost all you needed to do was the next time is play like a spoiled brat and double up and bet $5. Once you kept doubling sooner or later you had to win. As soon as you won, you were back to even. Even on that one hand.

So you keep their money when you won but you keep doubling down when you lose. So after you had done that long enough each day to pocket 100 of the winners, you would cash out for $500 and go home and watch Jeopardy and Wheel of Fortune. Do that 6 days a week, that’s $3000 a week. Better than working.

For $5,000 dollars, the nest egg you always had to take – (actually $5120) would buy you 11 double up’s, right?

Who ever heard of loosing more than 11 hands in a row. I couldn’t ever remember loosing more than 4 or 5 in a row.

Statically I was wrong. When you flip a coin 100,000 times there is something like 6 times that you could land either on heads or tails 17 times in a row. Now that’s what I don’t remember. These last numbers , the 6 times @17 in a row. The model we did before showed that the overall risk is exactly the same. One day before long you’d lose your $5000 risking it each time trying to win $5.

This from Grant Thompson, much more of a math whiz than I’ll ever be.

Ok, here is the deal. The probability of an event is unrelated to the number of times that the event may occur during a finite time interval. This is because the probability is an average number determined over many trials. This means that even though the chance that you could lose 10 times in a row is very small, it might happen to anyone at any time. The other important factor to remember in blackjack is that all players are not equal and it is not like flipping a coin. Some players do much better than 50/50, some worse.

Now, regarding the numbers, if you had $5,115, you could double down 10 times. Supposing that the probability of losing each hand is 50/50, the probability of losing each hand is 0.5. With this it is easy to calculate the probability that you will lose 10 times in a row. It is (0.5)**10, or 0.5 raised to the 10th power. The result is that there is a 0.098% probability that you will lose a coin flip 10 times in a row, anytime you sit down to play. That is a very low number, but remember that it can happen anytime. Let’s also suppose that you are a poor player and that your probability of losing is greater, say 0.75 instead of 0.5. Then there is a 5.63% probability that it will happen! Much more risky.

More from Grant Thompson:

Ronnie you are correct, sort of. The problem with your logic is 1) the odds are not in your favor and 2) you may have to risk an enormous amount of money just to break even. I did a few calculations and estimate that the odds of losing at the blackjack table 20 times in a row are about the same as dying in an auto accident. Now I think you will admit that this event is possible. If you doubled down an original $5 bet 20 times in a row, you would be putting $2.6 million on the table on the last play, then when you win you will be even and have to start all over again.

Even more from Grant:

Ronnie just to close this one out – not only is it possible if you play a lot – it is equally possible the first time you sit down at the table – thus the terminology – a game of chance

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