Use the cards to practice almost any basic math operations in a game. Remove all but the number cards from the deck for play. Deal out 10 cards to each player.
Perhaps the simplest game is to practice greater than and less than, as described in this post at thisreadingmama.com
Or, go for an addition, subtraction and/or multiplication practice game. Choose the math operator for the game, or use a dice with 1&3 for addition, 2&4 for subtraction, 3&6 for multiplication. Start with the first player (throwing the die if that’s how the game is being played, then) laying down any one of their cards and starting to count to 10, or 5 or 3, depending on the age of the players. Before reaching that magic number, the next player to the right has to lay down one of their cards AND announce the correct answer. If they get it correct, that player gets a replacement card from the pile and (throws the die, and then) lays down another card to re-start the process. The winner is the one left with cards when the other players are out, or the one with the most cards when the time is up.
You’ll obviously need to be around to verify answers, but that’s a small price to pay for good math skill building disguised as fun.