Contrary to popular belief, card counting is not memorising what cards have been dealt so that you can work out what cards are left in the deck(s). To begin with, unless you're Dustin Hoffman in Rain Man, you can't keep track of what's been dealt from six decks of cards. On top of this, only four or five of the decks are actually dealt before a reshuffle.

	Tthere is no certainty, but there are ways to estimate the ratio of cards left in the deck

In short there is no certainty, BUT there are ways to estimate the ratio of cards left in the deck.

If there are a lot of lower cards, say 6s and below in a deck, then your play should start to change. To maximise your chances you will hit more often, but double down and split less. The dealer's chance of busting is also greatly reduced.

In a deck with a lot of 10s left, the opposite happens.

Card counting involves attributing points to the various cards you see and keeping a running total. For instance, you score -2 for a 10, -1 for a 9, 0 for an 8, +1 for a 7 and +2 for a 6 etc. Every card you see, you add or subtract from the score to give you a positive or negative number.

This is your count total. You then divide the total by the estimated number of decks left to deal. For example, if the count is running at -12 with roughly two decks of cards remaining to be dealt, then the true count is -6. This means that there are a significant number of smaller cards left in relation to the 10s. Therefore, your playing and betting strategy should change.

It sounds simple, but it's fiendishly difficult to accomplish in a busy casino environment.

You'll find much more advice on card counting, adjusting your bets and a complete system in our main card counting article on this website.