This ability can greatly improve a player's capacity for making wise choices while playing the game. Through keeping track of which cards are picked up and which are discardedjoin rummy, players can determine the probability of drawing particular cards that could finish their melds. If a player discards a 7 of hearts, for example, it's important to keep in mind that this card is no longer usable by anybody else. It might mean that several players are working on related runs or sets if they are discarding cards from the same suit.