Memorize the values of each card.\n\n Start at 0 and as each card comes up, add it to your tally. Cards 2-6 have a value of +1. Cards 7-9 have no value. Cards worth 10 have a value of -1.
Blackjack is played with a conventional deck of 52 playing cards and suits don't matter. 2 through 10 count at face value, i.e. a 2 counts as two, a 9 counts as nine. Face cards (J,Q,K) count as 10. Ace can count as a 1 or an 11 depending on which value helps the hand the most.
