In Rummy 500, aces can be either high or low depending on the meld they're part of. An ace can be played low in a sequence as part of A-2-3, where it acts as the lowest card. An ace can also be played high in a sequence as part of Q-K-A, where it acts as the highest card. However, an ace cannot wrap around a sequence—you cannot play K-A-2, as this would be invalid. In terms of point value, aces are worth 15 points if left in your hand at the end of a round. This flexibility makes aces valuable cards in Rummy 500, as they can help complete sequences in multiple ways, but players must still follow the basic rule that sequences must be consecutive ranks without wrapping.