Now I'm not sure how the penalty for not answering questions work. However, I have read somewhere that GMAT reduces your raw score by the percentage of questions un-answered (I can't recall the source though).
So, 1 question un-attempted would lead to a 2 percent reduction.
"Wherever you go, go with all your heart" - Confucius
1. How to Review and Analyze your Mistakes (Post by BB at GMAT Club)
2. 4 Steps to Get the Most out out of your CATs (Manhattan GMAT Blog)
My Experience With GMAT
1. From 650 to 710 to 750 - My Tryst With GMAT
2. Quest to do my Best - My GMAT Journey Log