Hi Elonmusk1857.
Going from 510 to 700+ in 30 days is going to be pretty hard, but if you want to give it a shot, I have some ideas for you.
But first, let's be clear, having suicidal thoughts over a GMAT score doesn't make sense. You can apply to schools next year. You can find another path to your dream career. Regardless of whether you get into your dream school in R2 this time, life will go on.
Regarding how to increase your score, studying 12 to 15 hours a day might be too much. You may get burned out. So, see what works to find the max amount you can prepare each day.
Regarding quant specifically, you can do two things:
- work topic by topic to address weaknesses and get stronger in more topics
This post discusses some aspects of working topic by topic.
The Best GMAT Practice Methods- improve overall accuracy
This post has tips on improving accuracy.
Improving Your Accuracy on the GMATRegarding verbal, you need to do the following:
- fill knowledge gaps by learning concepts from a good test prep resource
- learn strategies for answering each type of verbal question
- practice to master getting verbal questions correct
For a detailed discussion of how to increase your verbal score, see this post.
How to Score High on GMAT Verbal