Play Blackjack With Your Kids (Really!): How Card Games Add Up to Learning! by Heather Bragg

OK, it doesn’t have to be blackjack necessarily! Any card game that asks children to compare, add, subtract or estimate numbers is a great activity for developing number sense, which is the foundation for future math mastery. 

Preschoolers can play comparison card games like “War” (I rename it "Number Battle" and take the face cards out to keep it simple). From kindergarten on, children can step up their (renamed) “War” game by flipping two cards at a time, adding the total, then comparing the sum with their opponent’s. They can also play a blackjack-like game where they pick cards and add the total, trying to get as close to a designated number without going over. 

Feel free to customize the card game of your choice based on your child’s age and mathematical prowess!