Hi abhishekshukla1995,
Since you have not studied math in quite some time, you probably want to take a slow and steady approach to relearning the math tested on the GMAT, ensuring that you are able to master the fundamental concepts of GMAT quant prior to moving on to more advanced topics. So, for example, you might start with basic fraction operations (addition, subtraction, multiplication, and division), manipulation of base algebraic equations, solving quadratic equations, basics of data sufficiency, etc. Once you master those basic concepts, you will find it much easier to learn more advanced GMAT quant topics.
When studying GMAT quant, since there is so much content to learn, you may find it helpful to take an approach that allows you to learn one topic at a time and follow up your learning with specific practice. In other words, you want to master one topic before you move to the next.
For example, if you are reviewing percents, you want to make sure you cover as much as possible about percents: percent less than, percent greater than, variable percents, and percent change. Then you will want to do many practice problems on percents (50 or more). The results of that practice will help you determine how well you have mastered that topic. Such a process will be helpful for all topics tested on the GMAT.
With regard to study materials, there are many options to help you with GMAT quant. To determine which course may be the best fit for you, you can check out the verified course reviews here.
Most online study courses also offer some sort of free or low-cost trial. My course,
Target Test Prep, offers a full-access $1 trial that expires after 5 days. The course is quite robust, with 20 chapters and 3,000+ practice GMAT quant questions. Additionally, we've been able to help students who, like you, have needed help relearning all aspects of GMAT quant.
If you have any further questions, feel free to contact me directly.
