Twenty One Game Tips:

Don't bet the max (half your bank) every round. This does not apply when you have under $100 ... but once you do, you don't want to start all over again if you lose one round of #21.

The best security, when playing, I've found to base your bets on the fact that you WILL lose eventually.

Here is an example (you'll start with a lot less money, but the principal will work scaled down as well):

Lets say you have $30000 in the bank. How much would you bet? I'd say bet $3000. Why? Lets say you lose. You are now down to $27000. Not bad. How much do you bet now? Answer: $4000. Why? If you win, you double it to $8000, which leaves you with $31000. Not bad ... you still gain even when losing. Lets say instead of winning with the $4000 bet, you lost a few more times... lets do the math (assuming you have $30000, and was in a loosing streak):

Money bet ----- BANK  ------------- Money gained if you win:

$3000 --------- $27000 ------------ $33000

$4000 --------- $23000 ------------ $31000

$6000 --------- $18000 ------------ $30000

$9000 --------- $9000 ------------- $36000

So you could play four games, loosing the first three, and still end up with a lot more money than you started out with. Course you'll have to do your own math adjustments when playing.

The end point is, while betting half your bank each time may be the FASTEST way to a high score, it is also the fastest way to LOSE. Making some account for the odds that you will lose once or twice will bring security to a game that is based on numbers :)