BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

What is the greatest common divisor of positive integers m a

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

What is the greatest common divisor of positive integers m a

by Max@Math Revolution » Fri Jun 21, 2019 12:54 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

[GMAT math practice question]

What is the greatest common divisor of positive integers m and n?

1) m and n are different prime numbers
2) m and n are consecutive integers
Top
Source: — Data Sufficiency |
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

by Max@Math Revolution » Sun Jun 23, 2019 5:14 pm

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

=>

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

The first step of the VA (Variable Approach) method is to modify the original condition and the question. We then recheck the question. We should simplify the conditions if necessary.

Condition 1)
m and n have a unique common divisor since 1 and m are the only factors of m and, 1 and n are the only factors of n. This tells us that gcd(m,n)=1 and condition 1) is sufficient.

Condition 2)
Since the greatest common divisor of consecutive integers is 1, condition 2) is sufficient.

Therefore, D is the answer.
Answer: D

Note: Tip 1) of the VA method states that D is most likely to be the answer if condition 1) gives the same information as condition 2).
Top
Legendary Member
Posts: 2214
Joined: Fri Mar 02, 2018 2:22 pm
Followed by:5 members

by deloitte247 » Sat Jun 29, 2019 10:34 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

Statement 1
m and n are different prime numbers
If m = 3 and n = 5 ; h.c.f = 1
If m = 5 and n =7 ; h.c.f = 1
The h.c.f of m and n = 1
Statement 1 is SUFFICIENT.

Statement 2
m and n are consecutive integers
Any two consecutive numbers will be a pair of ODD and EVEN numbers and their H. C. F is always 1

If m = 3 and n = 4 H. C. F = 1
If m = 4 and n = 5 H. C. F = 1
The H. C. F of m and n = 1
Statement 2 is SUFFICIENT.

Each statement alone is SUFFICIENT.
$$Answer\ is\ Option\ D$$
Top
Post new topic Post Reply
• Page 1 of 1