The dark art of counting cards at the game's table has always been a mainstay of many professional blackjack player's arsenal. But casinos have gotten wise to the practice. In order to mitigate the effects of counting cards, casinos have introduced both automatic shuffling machines as well as multiple decks for each game. This certainly throws a spanner in the works. Having said that, if you can master blackjack deck estimation, then you can move the odds ever so slightly more into your favour.