Let me say that you ask a very important question. It is one of the first topics that I mention to students and something I write about frequently. Let me add to what Tommy has already mentioned.
Here is an article on the types of procedures you might want to put into place to help avoid those Silly mistakes:
https://www.beatthegmat.com/mba/2012/10/ ... -handrails
And here is an article that deals with the importance (to your score) of not missing those easy questions:
https://www.beatthegmat.com/mba/2012/12/ ... n-the-gmat
The following is from an earlier posting that I made here
https://www.beatthegmat.com/best-practic ... tml#554834
"Not all errors are created equal.
When you see that you need to review fundamentals - like formulas or equations that is actually a relief! GMAT Test-takers are pretty good at memorizing things since that is something that is encouraged in college. So if you missed the question because you did not know a formula or a point of grammar or something you will likely learn this and not make the same mistake twice or at least not more than about 3 times.
There are two other kinds of errors: First, errors in applying the formulas and techniques - such as "I did not see that I could use the difference of squares on this question!" With these errors you have to learn to see the GMAT in terms of WHAT YOU DO KNOW and apply that knowledge. For example, when you a see a circle there are a limited number of things that you could do with that circle. Learning what to apply when is the part of the GMAT that is never-ending! I am still seeing new ways to do things years and years later.
And finally there are the Bad errors. You mentioned making "dumb errors" or as they are called: "Silly mistakes." These YOU MUST ADDRESS and the sooner the better.
Not only do "dumb mistakes" really hurt your score, but they also undermine your practice sessions and tests as well. Think about it, the test is adapting to you, right? So if you miss questions you should get right on those practice tests then you are never going to see questions that are as difficult as you would see without those mistakes. So you do not really get a chance to fully see where the holes in your knowledge are or how well you can apply your techniques to the toughest questions.
I have written an article on the three types of errors. The first half is on the Veritas Prep Blog here:
https://www.veritasprep.com/blog/2013/01 ... -the-gmat/
Once you have stopped making the silly mistakes you are in the enviable position of being able to learn from each mistake that you make on a practice test!!! This means that if you have a lack of knowledge you can simply find the formula or other information. If you did not know that you could apply a certain technique - well now you do know! This is when the GMAT gets to be fun.
