Grab a deck of playing cards, and let’s go! Challenge your child to find the largest sums possible. Whoever can find the biggest answers gets the points! 
- One deck of cards (Print a deck.)
 - Pencil and paper (for each player)
 - Timer (optional)
 
- The object of the game is to win points by forming the largest sum.
 - Remove tens and face cards from the deck. If you have jokers, add them into the deck. Jokers will equal zero.
 - Shuffle the cards. Give each player six cards.
 - Players have exactly one minute to make a 3-digit plus 3-digit addition problem using the numbers on their six cards. Players should experiment and double check their work to ensure they have the largest sum possible.
 - The player with the greatest sum wins the round and one point. The first player to earn 10 points wins the game.
 
- For younger players, deal two or four cards and form 1 or 2 digit sums.
 - Adjust or remove the time limit.
 - Change the scoring so players earn the number of points in their sum. Change the name of the game to Think Big!
 - Change the name of the game to Small is Beautiful. Create subtraction problems instead.
 - Use more cards. Try adding four digit numbers or five digit numbers.
 - Work on place value. Have players try to create the largest possible 6-digit number with their 6 cards.
 
By William L. Gaslin, Charles Lund, & Martin M. Gaslin
from:
http://www.education.com/activity/article/im-the-greatest/