For 2 – 6 players.
Setup: Take the 100 array cards, shuffle them, and deal five cards to each player. Place a card with the factors (not the product) face up, and put the deck beside it.
Goal: discard all of your cards. Whoever can get rid of all their cards first wins.
Players take turns.
On a turn, play a card on top of the discard pile.
You may play a card if one factor matches the card below it. For example, if the card on the top of the discard pile is 4 × 5, then you could play 7 × 4, since the cards share a factor (4).
Say the product (“28”) or the equation (“7 × 4 = 28”) as you play. If you’ve said the correct product and matched with the card below, the next player takes their turn. (Or if no one speaks up to correct you, the next player takes their turn.)
If you said the wrong product (“7 × 4 = 26”) a player challenges you by saying “correction” and giving the correct product (“7 × 4 = 28”) you take back your card and they can play ANY card from their hand on top of the discard pile, even if it doesn’t match the factors of the card below. Play then continues as normal. If it’s your turn and you don’t have a card that matches the factors of the top card on the discard pile, draw cards until you have a legal play.
If you have a square array in your hand, you can play it on top of ANY card, without matching factors. (You still have to name the product correctly to play it.) Then you can discard a second card of your choice on top of the square. The second card does not need to match the factors in the square, but you do need to say the correct product to play it.