Quantitative section was a tough task for me. The main problem for me was getting the correct answer in just a span of 2min. So to deal with this, I thought of it in another way. The test makers are not there to test how efficient I am with mathematics, but to check how I manage to recollect data I have with me and use it. They make questions disguise in a different way. They are tricky but they also have a simpler and shorter approach of solving it. The thing to remember is, it is the test which evaluates how you think and not what you know
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Firstly the problems in quantitative section can be solved by different ways; using regular traditional method, mathematical shortcuts, back solving and picking numbers.
In GMAT pattern you are needed to solve 37 questions in 75min, this leaves you with 2min for each question. You need to be quick and efficient while solving problems. So the traditional and lengthy method for solving each problem may not work. You may run out of time and some questions can remain unanswered. Going step-by-step to the answer can just consume your time. So it will be a suggestion to go for this method only when there seems no other way to carry out the problem.
You should know the tips and tricks for carrying out operations in mathematics. They are very useful and will help to solve problems in a less time. Knowing properties and generalized thumb-rule of various topics can prove savior for you in case of running times. For example if you know 30-60-90 triangle property then it will be much easier for you to calculate its area or perimeter. The time you saved in one problem can be put in solving another problem which requires you to think more on it. While choosing your mathematical shortcuts and tricks, be sure they are universal and can be applied to any variation in the problems. If the rule has any exception you must be aware of it.
If you do not know any mathematical shortcut for a particular problem, then you can try back solving. First you read the questions and look into the options. You get an idea of what answer you can expect. Sometimes it requires you to multiply huge number and the answer will also be a greater number. If answers are given in exponential form or in other different manner, you can work out your problem in that way. This even saves your time. Only thing you need to consider is you should be solving it in a relevant way, you should not roam around the bush.
Sometime you can use directly your options to answer. You can put values in the given function and see if it satisfies the function. You scan even choose numbers; negative, positive, even, odd etc. to check validity of your answer. You will always need extra layer of strategy for solving problems in GMAT. It requires much of your gray matter.
Another thing is to remember is ‘Practice makes man perfect’. You will skill your method of solving only when you will practice it enough. The next thing is your revision; review your work and methods for better understanding and less error future. Practice and revision of your work will surely improve your score.