Math Games: Addition and Subtraction War

I am hoping to update each week with an easy math game that can be played at home to practice and improve math skills. Most of the games can be played with number cards (cards labeled with 0-9 and a dot pattern) or with a deck of face cards with the King, Queen, Jack and Joker removed.

Addition War:
Divide the cards into 2 piles. Each person flips over the top two cards and adds them together. Then the person with the highest sum or total gets all 4 cards. For example, player 1 gets 5 + 7 = 12. Player 2 gets 3 + 6 = 9. So player 1 takes all 4 cards and sets them aside. If there is a tie, both players flip over their next two cards and the winner of that round takes all 8 cards.

Keep playing until cards in your pile are gone. Then count how many cards each person collected. The person with the most cards wins.

Subtraction War:
Divide the cards into 2 piles. Each person flips over the top two cards and subtracts the smaller number from the bigger number. Then the person with the highest answer gets all 4 cards. For example, player 1 gets 7 - 5 = 2. Player 2 gets 6-3 = 3. So player 2 takes all 4 cards and sets them aside. If there is a tie, both players flip over their next two cards and the winner of that round takes all 8 cards.
Keep playing until cards in your pile are gone. Then count how many cards each person collected. The person with the most cards wins.