There is a cool game for multiplication at BigBrainz.com. You can download it for free for the basic game - then they will send you a $5 code for the whole version for $19.99 which I got. DS is 9. The game is called TimesAttack. Basically, an alien is trapped in a dungeon and you have to do your multiplication tables to get him out. You go thru the castle and to open the door, you must first do one of three of the two times tables (i.e. 2x4, 2x8, 2x11) then you will fight a small ogre after each one until you complete all three. You do the same thing for three more groups of three and then you fight a big ogre with all 12 numbers. If you get them all right, you move on to the threes times tables. If you miss any, you repeat the ones you miss then fight the big ogre for all 12 numbers. It really tests what you know and adjusts to help you get the ones you keep missing.
The basic game is the ogre thru the whole castle. In the upgrade, you do a spaceish level fighting robots and a lava level fighting flying dragons. The upgrade makes it less redundant.
This really gave DS9 a fun way to practice his multiplication tables. It helps them answer them quickly because you are timed.