Have questions about your preparation or an upcoming test? Need help modifying the Study Plan to meet your unique needs? No problem. Just book a Skype meeting with Brent to discuss these and any other questions you may have.

- Video Course
- Video Course Overview
- General GMAT Strategies - 7 videos (free)
- Data Sufficiency - 16 videos (free)
- Arithmetic - 38 videos
- Powers and Roots - 36 videos
- Algebra and Equation Solving - 73 videos
- Word Problems - 48 videos
- Geometry - 42 videos
- Integer Properties - 38 videos
- Statistics - 20 videos
- Counting - 27 videos
- Probability - 23 videos
- Analytical Writing Assessment - 5 videos (free)
- Reading Comprehension - 10 videos (free)
- Critical Reasoning - 38 videos
- Sentence Correction - 70 videos
- Integrated Reasoning - 17 videos

- Study Guide
- Your Instructor
- Office Hours
- Extras
- Prices

## Comment on

Prime Divisors## Hey Brent,

Why dont we consider 1 also to be one of the prime factors of 8500 along with 2,5 and 17.

## 1 isn't a prime number.

1 isn't a prime number.

From the Official Guide: "A prime number is a positive integer that has exactly TWO different positive divisors, 1 and itself."

1 has only one positive divisor, so it is not prime.

## My Bad. Thanks for reminding!

## Would total number of prime

## Good question.

Good question.

Yes, without the word "DIFFERENT," there would be 6 primes in the factorization of 8500.

Cheers,

Brent

## Hi Brent,

What questions can be answered wrongly if we don't include 1 into consideration?

Thank you in advance,

## If you don't include 1 as a

If you don't include 1 as a divisor (aka factor) of a positive integer, then you risk incorrectly solving questions involving the divisors of numbers.

Consider this Data Sufficiency (partial) question:

What is the value of positive integer n?

Statement 1: n has exactly one positive divisor.

If you don't consider 1 as a given divisor of n, then you'll (incorrectly) conclude that statement 1 is insufficient, since n could equal 2 or 3 or 5, etc

Cheers,

Brent

## Hi Brent,

This is a very useful insight,

Thank you very much

## Add a comment