Here's why:
* Ace as a high card: The ace is the highest card in a standard deck, so it can be used to complete a straight with the cards 10, Jack, Queen, and King.
* Ace as a low card: The ace can also be used as the lowest card in a straight, completing a straight with the cards 2, 3, 4, and 5.
Examples:
* A-2-3-4-5 is a straight (Ace as the low card).
* 10-J-Q-K-A is a straight (Ace as the high card).
Important Note: An ace cannot be used to complete a straight that wraps around from King to 2. For example, you can't use an ace to complete a straight with Queen, King, 2, and 3.