How study Sat math on phones?

I am getting ready for SAt test. I don’t like reading from books to study math because it is hard to carry.

Are there good applications I can use in my iphone? I also plan to buy ipad if it helps to study math. Do you suggest using ipad to study the math section?

Can you tell me which applications I should start using?

I have found a great site to study maths and make up your own tests.
It is Maths Test