Write a variety of decimals on index cards, ranging from small decimals to large. Create at least 50 cards. Not all the cards need to have a different decimal, the decimals can repeat from card to card.
Lay out all the cards, decimal side down on the table so only the plain backing is visible to the players.
Seat the players around the table and instruct them to take turns flipping over two cards. If the two card when added together create a whole number or higher, they can remove the card from the layout and place them in a pile beside them. If the two cards flipped do not equal a whole number then they must turn the cards back over.
Tell a player who turns over two cards that form a whole number to take another turn. The player can continuing taking turns until he fails to make a whole number from the two decimal cards flipped over.
Instruct the next player to flip over two cards, and so on. As the game progresses, the players will have to remember which card was where and also add the decimals in their head as they contemplate their next choice.
Count all the cards each player has acquired when there are no cards left or if none of the cards left, when paired, form a whole number. The player with the most cards wins.