Hey There !
I would recommend that you have a look at this thread for operations on exponents and for other quant concepts.
https://gmatclub.com/forum/math-number-theory-88376.htmlAlso, if you're struggling with basics of quantitative aptitude, would recommend you to check out "GMAT Foundations of Math" by Manhattan. I also believe the foundation course is available free of cost on Manhattan's website.
You can check out the mentioned course to brush up the fundamentals concepts in quant.
Also - GMAT Ninja has a complete quant series on his youtube channel, you can check that as well as an additional resource.
Hope you find this useful.
Cheers !