DD on any number of cards adds .23% to players advantage.

The game changes so often. It used to be that the regular game, Las Vegas Advisor would list the few casinos that allowed Double Down after SPlt. Now it appears that 30% of the casinos allow this. It's always a fight for something that will attract business. By the way, DDAS .12 to.14 advantage. (14 cents per $100?)

As always, since I have friends who like to point out that once they once split 8s three times and doubled each time against a dealers 6 (blah, blah, blah) and because of that all my odds and percentages mean nothing to them. ;-)

Knowing the odds won't make you a winner, but it will keep you from making bad bets and increasing your chances of being a loser! So for those who insist on throwing down $25 on the "Yo" because it's a hunch, they just skewed the odds heavily in the casinos favor.