I am no expert on medicaation for such issues, so, I will limit my comment to careless errors in math which I have a lifetime of experience with.
If careless errors are the cause of her failing in math tests, you need to address that regardless of what the psych test results bring forth. Don't pin all your hopes on medication alone to fix this - you need to address the issue and work on it with her as well.
I second what syolblrig said. Either get her a math tutor or if you can tutor her in math, get a strong curriculum and afterschool her. A fair amount of drilling in math basics is needed before a child develops automaticity in math operations to the extent of not making careless errors. You can get her to take a placement test in math to see where she is at. Sometimes, kids can get the concepts in math easily, but may need a lot of practice before they can uderstand how to apply those concepts to problem solving.
Good luck.
