Playlist title Testimonials Video source Manhattan Review Video category GMAT Watch more videos: GMAT Official Guide 13: Data Sufficiency 174 17. GMAT Math Lesson: The GCD/LCM Formula 8. Answering CR Questions from the GMAT Official Guide 16. GMAT Counting Lesson: When to use Combinations GMAT Tuesday: Don't Fear Mistakes GMAT Official Guide 13: Data Sufficiency 94