If you know how to play Rummy the basics are the same except the matches are a number plus an equation, playing from the cards in your hand, including cards on the table too.
If you are not familiar with Rummy each person is dealt five cards. The left over cards are placed face down between the players and the top card is flipped up. The card will either be an equation that must be solved by the card player, or a whole number that you must match to an equation selecting from the cards in your hand. The cards you are dealt will either be an equation or whole number.
The person to the left of the dealer goes first. If the player can make a play on the face up card by matching a card in their hand to an answer they pick up the card make their play and lay the cards down in front of them and continue to play until there are no more matches.
There are a few more finesse points but basically in order to play the game you must know your math tables. The draw of fun for most children is irresistible even if they have to learn along the way.
Jennie has been a teacher for many years and came up with this game and copyrighted it. She reports the students she tutors love playing the game and learn much more quickly than traditional methods. They learn the math because the game is fun and they have a strong desire to win.