Knowing that the experimental questions can be disproportionately difficult, if you do poorly on a particular question you can take some solace in the hope that it may have been experimental. In other words, do not allow a few difficult questions to discourage your performance on the rest of the test. The only thing that has changed is medium, that is, the way the questions are presented. One the other hand, you cannot return to previous questions, it is easier to misread a computer screen than it is to misread printed material, and it can be distracting looking back and forth from the computer screen to your scratch paper. Although time is limited on the GMAT, working too quickly can damage your score.
Many problems hinge on subtle points, and most require careful reading of the setup.
Because undergraduate school puts such heavy reading loads on students, many will follow their academic conditioning and read the questions quickly, looking only for the gist of what the question is asking. Once they have found it, they mark their answer and move on, confident they have answered it correctly. Later, many are startled to discover that they missed questions because they either misread the problems or overlooked subtle points. The two major parts of the test are scored independently. The average total score is 500.