Most playing cards have some sort of design on the back. Here’s one option you can copy onto the back of the cards in these sets. This particular design has small heart, spade, diamond, and club images arranged from top to bottom in a straight line. Print the number cards first, then arrange them in your copier to print these on the back side. You may want to do a test run first to make sure they print right side up on the back of the cards. Then cut the cards apart. You may want to laminate them before having your kids play with them.
1 page with the backings for 8 cards
Go to this page to see all the number cards 1-20 playing cards.