I have the GMAT premiere 2012 to help me and I've made it 100 pages in and have some difficulty understanding the math that is presented to me.
Regarding this - note that books can only help you so far. Studying and reading 100 pages might be helpful for some people, but you'll certainly internalize a lot more if you learn by watching someone else answer tough questions. Learn what exactly is going through their mind and what they are focusing on, etc.
Also, you can download the free GMAT Pill
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