CAT environment, especially GMAT CAT environment is different from your traditional paper based exams. Remember the following tips before you write your GMAT
1) Don't Stare at the Computer
First, you will find that you are spending a lot of time looking between the screen in front of you and your dry erase board. USE YOUR PEN AND DRY ERASE BOARD (but do not waste valuable time writing needless things down). One of the worst things you can do is to waste time staring at the screen. Do not make this mistake. Instead, you should get in the habit of immediately writing down ABCDE on your board for every question (When studying, I used pencils and paper, but on test day you will have dry erase markers and a laminated sheet that you can use to write things down). This should be a habit as you study for the GMAT, they don't give you material to write things down for nothing.USE IT! This way, you can immediately eliminate answers that you know are incorrect (And on a separate note, there are tricks for elimination strategies on the Quantitative Data Sufficiency questions, will be posted within the Quantitative Forum).
2) Don't try to remember the answer choices - Write it Down
Don't waste your valuable brainpower trying to remember answers that might be right or wrong, WRITE THEM DOWN! You have no idea how many times you will be very appreciative of doing this when you look down and see that you have two answers to choose from instead of trying to look up at your screen and trying to remember what answers you told yourself to eliminate. Even if you don't know the exact answer, your test scores will be drastically improved if you can eliminate even one or two incorrect answers. If you can eliminate three incorrect answers, your probability of guessing the right answer is 50%! So be sure to get in the habit of writing down ABCDE and then crossing answers out as you go.
3) Read the Questions Carefully
Read the entire question carefully and write down the useful information (this is more geared for the Quantitative part). Don't worry about writing everything down at first, but as you practice, you will become more proficient at identifying the key pieces of information. With easy questions, you won't have to write down much, but with your ABCDE and key pieces of information, you will have essentially transferred the problem from the computer screen to your paper/board and will make your life much easier, as you will be able to make equations, draw pictures, do whatever you need to do to eliminate answers. BUT, a key here is to make sure you transfer information correctly. The worst thing you can do is to write down wrong numbers or facts, etc. I can't tell you how to become a pro at accuracy, but in general, work slow to work fast. Once you are certain you have it down in front of you, go to town on cracking the problem. Eliminate answers as you go.
4) Prepare with Computer based Mock tests
Another issue with CAT test prep is that it is difficult to simulate the test day environment. That is where prep services like Grockit come in. Become comfortable with using the computer to answer questions, it will be invaluable come test day. I'm sure that you will employ traditional book based studying (such as Official Guide for GMAT Review) and I highly encourage you to use such books. But as you become comfortable with the material itself, it is essential that you are able to transfer your mastery of the material to a CAT environment. Supplement your computer testing with your paper (book) testing and vice-versa. Don't become too comfortable with studying out of books, but use that practice to become a master at translating the key pieces of information to your scrap paper/dry erase board.
By employing the above methods, it will help you become a master of the CAT environment and will definitely pay dividends come test day. USE YOUR DRY ERASE BOARD, WRITE DOWN ABCDE, and good luck!
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About the Author

I am Atul Jose - the Founding Consultant at F1GMAT.
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