Remove the face cards and the tens from the deck of cards.
Have each student draw a 4 x 2 box on their paper. (4 spaces accross and 2 spaces high)
Shuffle the cards and draw the top card from the deck. The students must then write this number in one of their boxes. Once the number is placed it may not be moved. Draw the next card from the deck and have the students write that number is one of the remaining 7 boxes. Follow this procedure until all the boxes have been filled.
The students are then to add these two four-digit numbers. The student with the largest number wins. (I usually give a small piece of candy or gum.)
Continue playing with a new 4 x 2 box.
The students will soon develop a strategy of putting the largest numbers in the left most boxes.
You can use any size box. 4 x 3 if you want to add three numbers.
I also use this to practice subtraction. The person with the smallest number in the end wins. If the top number ends up smaller than the bottom number and subtraction is not possible - then the student is out of that game.