Ghostblasters is one of those super simple math game sites that is great because of its simplicity. It only practices one skill - identifying multiples. You can set the multiple to whatever you want on the ghost that pops up on the screen - then click start and up pop the ghosts! You have to be fast to click on the multiples of whatever you selected (a mouse is probably better for this than a mouse pad).
It's one of those quick and easy things you can use for a reward, or individual practice that the kids just can't get into trouble with. They find it pretty exciting once they get the hang of it.
No ads, no sign in, no registration, no side menus that can lead them astray to other games or sites - just Ghostblasters.