Starfall (traditionally reading only) has really stepped up its game for Math with the premium side. It works wonderfully with K-2.

I know that Everyday Math has multiple apps out that goes along with their curriculum.

You can take a look at the link on a site I have put together to use with 5th grade everyday math https://stevenson.sd54.o...

www.mindresearch.net/pro... Foe iOS game-based instructional software for K-5 and secondary intervention and is designed to boost math comprehension and proficiency through visual learning

some good stuff here too www.ixl.com/

Elementary School Math HD

Sumdog.com - Grades 1-6