I've explained to Joey how much easier math is when you have all the basic operations memorized. It's like being able to sight read a large number of words. And the only way to get good at either of these things is practice. (As you can tell, we don't unschool around here... not yet anyway.)
And, not surprisingly, anytime I ask her to practice her math facts she balks.
Until we started playing with these...
You can do this with regular dice, but you'll only get practice with 1 thru 6. These are role playing dice for Dungeons and Dragons. I'm guessing you can get them at comic book shops.
We've come up with a couple of games and I'm sure there are many more to be discovered.
Game 1- Each person takes two dice and, on the count of three, they toss them. As fast as they can, each person shouts out the sum of the dice (or the product or difference, depending on the game). You can make it more difficult by tossing 3 (or 4) dice each.
Game 2- One person rolls two dice where the other person can't see. Then they say, "The sum of these dice is X and the product is XX." The second person then figures out what the two dice are or, to make it slightly more difficult, they figure out the difference between them.