If the area of a number

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BTGmoderatorDC: Moderator; Posts: 7187; Joined: Thu Sep 07, 2017 4:43 pmFollowed by: 23 members

by BTGmoderatorDC » Mon Nov 27, 2017 3:24 pm

If the area of a number is defined as the difference between that number's greatest and least prime factors, what is the area of 100 ?

A. 0
B. 2
C. 3
D. 5
E. 9

How to find the area?

OA C

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Source: Beat The GMAT — Problem Solving | Mon Nov 27, 2017 3:24 pm

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Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Mon Nov 27, 2017 3:49 pm

lheiannie07 wrote:If the area of a number is defined as the difference between that number's greatest and least prime factors, what is the area of 100 ?

A. 0
B. 2
C. 3
D. 5
E. 9

This question begs us to find the prime factorization of 100
100 = (2)(2)(5)(5)
So, 5 is the GREATEST prime factor of 100
And 2 is the LEAST prime factor of 100

Area of a number = (the number's GREATEST prime factor) - (the number's LEAST prime factor)
Area of 100 = 5 - 2
= 3
Answer: C

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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EconomistGMATTutor: GMAT Instructor; Posts: 555; Joined: Wed Oct 04, 2017 4:18 pmFollowed by: 12 members; Thanked: 180 times

by EconomistGMATTutor » Tue Nov 28, 2017 4:41 am

If the area of a number is defined as the difference between that number's greatest and least prime factors, what is the area of 100 ?

A. 0
B. 2
C. 3
D. 5
E. 9

How to find the area?

OA C

Hi lheiannie07,
Let's take a look at your question.

In the first step we will write as a product of its prime factors.
$$100=2\times2\times5\times5$$

Largest prime factor = 5
Smallest prime factor = 2

As defined in the question statement:
Area = Largest prime factor - smallest prime factor
$$Area=5-2=3$$

Therefore, Option C is correct.

Hope it helps.
I am available if you'd like any follow up.

GMAT Prep From The Economist
We offer 70+ point score improvement money back guarantee.
Our average student improves 98 points.

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8139; Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members; Location: Los Angeles, CA; Thanked: 43 times

by Scott@TargetTestPrep » Sat Oct 05, 2019 3:42 pm

BTGmoderatorDC wrote:If the area of a number is defined as the difference between that number's greatest and least prime factors, what is the area of 100 ?

A. 0
B. 2
C. 3
D. 5
E. 9

How to find the area?

OA C

The greatest prime factor of 100 is 5, and the least is 2. Thus, the area of 100 is 5 - 2 = 3.

Answer: C

Scott Woodbury-Stewart
Founder and CEO
[email protected]

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