Hello experts, is the official material enough or should one also consult third part source(particularly SC)? Moreover, how many questions from SC GMAT prep are there ? Thanks
the official materials should be sufficient. if you think they aren't, then your studying has too much breadth and not enough depth.
there are a few hundred questions just in the freeware GMAT Prep. i don't know whether anyone has an exact count; certainly an exact count isn't important.