For Intermediate Ages
Number of players: 2 of equal skill level
What you need: Deck of cards, face cards removed (Ace=1) - 9.
What to do: The deck is placed between the two players. One card is turned over and the players double it to find the sum. The first player to say the correct sum out loud collects the card. Play continues until one player collects all of the cards. In case of a tie, the card is left on the table, play continues until one player says the correct answer before the other. The winner collects all the accumulated cards.
Example: Player 1 turns over a 7. The first player to say "14" collects the card.
Variation: Players must double then add 1 to find the correct answer. Once players are comfortable with adding 1 to the doubles, try doubles minus 1.