Primes and Prime Factorization and Multiples, LCM, and GCD | Six Minutes: GMAT Quant, Part 4

Six Minutes: GMAT Quant, Part 4: Primes and Prime Factorization and Multiples, LCM, and GCD: Number Properties: breaking numbers to primes; then Multiples, LCM, and GCD Learn to break any number into its prime factors by dividing with small primes in order. Then use the factorization to test divisibility instantly and count factors with the add-one rule. Then: Find the LCM and GCD from prime factorizations, taking highest powers for LCM and lowest shared powers for GCD. Learn which tool a word problem is really asking for, and dodge the product trap. Chapters 0:00 Introduction 0:25 What a prime is 0:50 How to break a number down 1:36 Counting factors from primes 1:58 Worked example 3:02 The trap 3:21 Recap 3:38 Multiples, LCM, and GCD 3:49 LCM and GCD 4:18 Which one do I need? 4:38 Worked example 5:20 Trap 5:42 Recap 5:57 Thanks for watching Practice problems 1. How many factors does 450 have? (Answer: 450 = 2 · 3^2 · 5^2, so (1+1)(2+1)(2+1) = 18 factors.) 2. Is 330 divisible by 11? (Answer: 330 = 2 · 3 · 5 · 11, and 11 appears, so yes.) 3. Three lights blink every 9, 15, and 25 seconds and just blinked together. After how many seconds do they next blink together? (Answer: 225) 4. What is the greatest number of identical goodie bags possible from 36 mints and 84 chocolates with none left over? (Answer: 12 bags, each with 3 mints and 7 chocolates) Six Minutes @SixMinuteClass: One technique, about six minutes. The narrator's voice is synthetic (computer-generated). Independent educational video. Not affiliated with or endorsed by GMAC (Graduate Management Admission Council). © 2026 Six Minutes · @SixMinuteClass