This is a game for two or more players. You’ll need a deck of cards, ace-nine (ace = one) for each group of players. Before the students play the game, review the number pairs that add to 10. Then have the students look for ways to use this knowledge to help them add and subtract faster.

Deal out all the cards, an equal number to each player. The cards are left face down in a pile in front of each player. The first person turns over a card and places it face up in the center of the play area. The next person turns over a card, adds it to the card already played, says the sum out loud, and places the card on top of the previously played card. The next person turns over a card and adds the card to the sum of the first two cards. Play continues in this way until someone has a card that, when added, will give a sum greater than 25. When that happens, the player must subtract rather than add.

Play continues until someone gets a sum of exactly 25. The player who gets a sum of exactly 25 wins that round and goes first in the next round.

from:

http://washmath.org/files/GamesAndActivities.pdf