As many as you want to have.
OBJECT: To get to 21 without going over.
SETUP: Give each player two cards, one face up, and the other face down.
PLAYING: Each player looks at their face down card, showing no one else. Add up the face value of the cards, face cards being ten and aces being one or eleven. If you need more cards to get to 21, ask the dealer for another card (hit). You may only get two hits. When everyone is ready, find out how many points everyone else has.
WINNING: The one who gets closest to 21 without going over.