Need clarification on finding Prime Factors

Question

Quant is not my strength, so this question may seem a bit silly, but when a question asks "how many prime factors does X have?" In general, does it mean unique prime factors?

For example the prime factors of 48, {(2^4), 3}
If a question asks, how many prime factors does 48 have? Would you answer two, or five? Will a question specifically ask for Unique Prime Factors if that's what it is looking for?

Harley1980 · Answer

Hello  meshackb 
When task asks about prime factors of a number, you only need distinct values. 
So 48 has two prime factors: 2 and 3

wakk0 · Answer

Hey  Harley1980 , can you provide an official example that deals with prime factors, and the official answer only means unique (without stating "unique" or "different" somewhere in the problem)? I was taking a look through MGMAT's Number Properties book (5th ed) and when they talk about counting prime factors they state that the total number of prime factors of 252 is 5 (2,2,3,3,7) (top of pg 96). On the previous page they talk about the different ways that factor questions can be asked, and they explicitly state "different prime factors" or "unique prime factors" when the answer should only be 2,3,7 - for the previous example. There are also some previous examples in the book when they mention prime factors they explicitly state all of the multiplicities.

I'm coming from an academic math background, so my understanding of prime factorization stems from that.

Harley1980 · Answer

Hello wakk0 . Here is example the-positive-integer-k-has-exactly-two-positive-prime-factor-60634.html in which task says that number k has exactly two primes. And after we solved task we can see that k = 63 so k = 3 * 3 * 7 and has 3 prime factors with repetions and 2 prime factors without repetions. So we can infer that GMAC count primes without repetions. But you are absolutely right: this is really uncommon case for official tasks. Usually GMAC questions avoid any ambiguity and clearly specify what we need to seek: "different prime factors" : how-many-different-prime-numbers-are-factors-of-the-positive-102487.html if-n-is-the-product-of-the-integers-from-1-to-8-inclusive-50953.html Or if they want include repetions of primes they mention it as "prime including repetions" : the-prime-sum-of-an-integer-n-greater-than-1-is-the-sum-of-167088.html and Manhattan example of task in with we should find primes with repetitions "prime factors, not necessarily distinct" : for-any-integer-k-1-the-term-length-of-an-integer-108124.html

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

Need clarification on finding Prime Factors

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards