# blackjack probabilities...

Discussion in 'Online Casinos' started by AdamD7, Jun 5, 2009.

Jun 5, 2009

Occupation:
Computer TECH
Location:
USA
I'm trying to find a website, etc. which displays the probabilites of losing streaks in blackjack.

example....

6 losses in a row = 1 out of 68 hands
7 losses in a row = 1 out of 100 hands
etc.......

anyone know?

2. Jun 5, 2009
3. ### thelawnetDormant account

Occupation:
programmer
Location:
UK
depends on whether you are playing correct strategy or not and also on the exact rules of the particular blackjack variant.

It's really basic probability this question, not so much something you need a website for - if the chance of an event occurring once in a row is p, then the chance of it occurring x times in a row is p ^ x.

the chance of a net loss in blackjack is 0.491.

So if you play 6 hands, then the chance of losing all 6 is .491 ^ 6 = 0.014 (1 in 71), and 7 is .491 & 7 = 0.007 (1 in 145).

The question of how often this will occur (which is what you've asked) is slightly more complicated, it is given by ?(p^-1 + p^(-2) + .. p^-n)

i.e. 1/.491+1/(.491*.491)+1/(.491*.491*.491)+1/(.491*.491*.491*.491)+1/(.491*.491*.491*.491*.491)+1/(.491*.491*.491*.491*.491*.491) = 138 for six hands

In other words, if you played blackjack over an extended period of time, you'd expect to have a run of 6 losing hands in a row every 138 hands (and 7 in a row every 283 hands). Note that is not the same as the inverse of the chance of winning 6 out of 6 hands - the reason is that the events (the sequence of losses/wins in a row) are strongly correlated.

Suffice to say it's not particularly unusual at this level. In fact, you need to get ridiculous numbers of losses in a row to have anything to complain about. When you are talking about 20+ losses (which would happen every 3 million hands), that's something to be unhappy about.

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4. Jun 5, 2009
5. ### RustyBanned User - repetitive flaming

Occupation:
IT
Location:
Manchester UK
Thanks Law,
Adam , assuming you are looking for anomalies in your BJ returns I would just like to add that you really need to look for more than just long losing streaks.
They can easily be broken up by a push for example.
You would be better served by looking at your wins and seeing how close to expectation those results are and of course if there are any anomalies in wins/losses on different bet sizes along with your overall return.

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