Did you find out what kind of questions give you maximum trouble ? Do you use any technique like an
error log to track your mistakes and weaknesses .
Once you know where you are weak, you can read some strategy books like
mgmat or veritas. This forum also has a wonderful collection of GMAT strategy stuff. Use these resources and improve on your weak area. To avoid silly mistakes the only option is to prctice more and be careful while solving the quant part.
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