Preparation

Remove the non-numbered cards (two instruction cards and two URL cards) from the deck.

Shuffle the deck well.  Since the playable deck comprises 68 cards, it may be difficult to shuffle all the cards at once.

The playable deck comprises four each of cards numbering from one (1) to 17.

Standard Game Play

Deal each player seven cards, face down.

Place the remaining cards in the middle of the table in a "Draw" pile.  Flip over the top card, face up, showing the number, to make the "Primed" pile.  The player to the left of the dealer starts the round.  After each round, the starting player of the previous round becomes the dealer of the next round.

Players try to use the topmost card in the "Primed" pile, and any single card in their hand, to add together to make a prime number, placing the card used on top of the "Primed" pile.  With the current deck, players can make the following prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, and 31.  If the player cannot make a prime, they must draw a card from the draw pile.  If they can make a prime using the drawn card, the drawn card may be played.  If not, the player's turn is over.  Play continues to the left (clockwise) until a player has no cards remaining, ending the round.  Players with remaining cards add up the cards' values and record the sum.  The player with the lowest total after four, or more, rounds is the winner.

Variations

• Composites:  Play the game as above, computing composites instead of primes, (e.g. 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30, 32, 33, and 34).  This mode is a sort of "avoid-the-primes" approach to learning prime numbers.

• Multi-card primes:  Players can use as many cards as possible, from their hand and the top card on the primed pile, to make prime numbers.  This variation may A) allow a player to exhaust their hand faster as well as B) enable the computing of much larger prime numbers (e.g. 9 + 13 + 14 + 17 = 53).

Playing Primed with a Standard Deck of Cards

We created the custom Primed deck in order to work with prime numbers up to 31.  However, as our primary goal is education, you can play primed using a standard 52-card poker deck as well, with 19 being the highest prime you can compute.  Simply remove all of the face cards (e.g. King, Queen and Jack) from the deck and play as above with cards numbered Ace (e.g. 1) through 10.