Use a deck of cards to play a game of addition war:
- Get a deck of cards and place them face down.
- The First player turns over two cards and adds the two sums.
- The Second player turns over two cards and adds the two sums.
- Compare the sums.
- The person with the highest sum gets to keep all the cards.
- Repeat until no cards are left.
- The winner is the player with the most cards.