I want to share with everyone the video explanations to all of the problems in the quantitative section of the Official Guide to GMAT 10th Edition. http://www.gmatquantum.com/og10/
Many people might wonder if this old guide is still relevant, and the answer is yes. The OG10
is fairly accessible and has around 714 questions, there is a significant overlap with OG 12
and the GMAT Quant Review 2nd Edition(Green supplement book) and I have color coded those questions. There are about 350 unique problems that are not present in the current official guides, and many of these are relevant to students struggling to grasp the basics, there are a fair number of difficult problems as well.
I have always emphasized practicing with actual GMAT questions, partly because the language and style of the GMAT test writers is unique and it is absolutely important to get used to how the GMAT writers phrase the questions. This is a common sticking point for many students.
And finally, one could also choose to skip buying the GMAT Quant Review 2nd Edition book, because 75% of the problems in this book are present in OG10
Free Video Explanations: OFFICIAL GUIDE FOR GMAT REVIEW 2015.