[Youthcantknow]

It sounds like you are doing exactly what your granddaughter needs. She's still receiving instruction in seventh grade math at school, after all. Meanwhile, even if she masters those formulas her mother is so fond of she still won't get the answer correct if she makes basic fact mistakes while solving them. She's also more likely to grasp those earlier skills more quickly because she's older and has more experience with numbers, so you should be able to move through the underlying skills relatively quickly, building her confidence and her understanding at the same time. I think you're doing great!