Marble Math Junior
Both the 4 year old and 6 year old frequently pick this to play, so it is fun for them. Adjustable levels for both kids. Not sure how fantastically educational it is though.
Math Bingo
Fun way to improve knowledge of math facts. Kids have a tendency to just play with the bingo bugs, though, once they get bored of adding/subtracting.
Visual Multiplication Table
I love this app. Great way to visualize multiplication. You need to show kids how to use it, and explain what they are seeing. And it isn’t the kind of ‘my kid is learning multiplication’ drill game they’ll play for half an hour. So some people will not see the value of this one. But I really think it is wonderful for *understanding* math, and an intro to its visual beauty, so important beyond drilling facts. I can imagine my 6 year old will get use out of this for years to come. A neat app.
Chocolate Fix
Great for developing logic skills. My 4 year old can do the easy ones with some help, and my 6 year old works on the easy and medium categories. I work on the hardest ones, and have fun with it when and IF I ever get the ipad to myself! Love this one. Try the free version, then upgrade to full. Highly recommend it. More fun that then math facts games, and maybe better for brain development too, than all the drills.