A system reads an identifier from a hand of cards to identify the cards. For example, the system can read an identifier from a pair of cards forming the initial hand in blackjack, where the one card is face up and the other card is face down. The system determines the value of a hand of cards form the read identifiers. For example, the system can determine a value of an initial hand of two cards in blackjack, while only one card is face up. The system can inform a dealer of the value, or status based on value, of the hand. The system can determine whether cards forming a hand of cards are authentic by validating the cards based on the read identifier. The system can determine if the cards forming the hand of cards are in an expected sequence based on knowledge of the initial sequence of cards in a deck. A decision tree to validate the results of the card game can be created to provide possible solutions or outcomes for each hand, and then, invalid solutions can be eliminated from the decision tree based on known card identities, rules of the game, possible outcomes of other player hands, and other information.