Can I score a Q50 without permutation and combination?

Yes, absolutely. I would greatly appreciate any help/advice. I have the test in 8 days and I currently believe to be at 70% in both V and Q.

First off, you could take one last MBA.com practice exam. Once complete review your wrong answers to determine some of your weak areas and make the necessary fixes in those areas. Additionally, you may find it helpful to engage in focused practice of each individual quant and verbal topic. For example, let’s say that you want to practice Number Properties. You can do so by answering 50 or more questions just from Number Properties: LCM, GCF, units digit patterns, divisibility, remainders, etc. As you do such practice, do a thorough analysis of each question that you don't get right. If you got a remainder question wrong, ask yourself why. Did you make a careless mistake? Did you not properly apply the remainder formula? Was there a concept you did not understand in the question? By carefully analyzing your mistakes, you will be able to efficiently fix your weaknesses and in turn improve your GMAT quant skills. Number Properties is just one example; follow this process for all quant and verbal topics.

I wrote an article that you may find helpful that has some more advice regarding how to treat the final week leading up to your GMAT as well as some tips for test day.

Let’s me know how things end up, and please reach out with any further questions.

Good luck!