Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Re: Is the positive two-digit integer N less than 40 ? [#permalink]

Show Tags

03 Dec 2012, 05:45

10

This post received KUDOS

Expert's post

12

This post was BOOKMARKED

Is the positive two-digit integer N less than 40 ?

(1) The units digit of N is 6 more than the tens digit --> the greatest possible value of the units digit is 9, thus the greatest possible value of the tens digit is 9-6=3, which means that N is less than 40. Sufficient.

(2) N is 4 less than 4 times the units digit. The same here: the greatest possible value of the units digit is 9, thus the greatest possible value of N is 4*9-4=32. Sufficient.

Re: Is the positive two-digit integer N less than 40 ? [#permalink]

Show Tags

03 Dec 2012, 08:14

1

This post received KUDOS

1

This post was BOOKMARKED

I solved it using method of substitution.

Given number(N) is 2 digit number. So, 0<N<100. So, Question is whether N<40

Case 1: If Number N is AB, AB => A (A+6). AB => 17,28,39. hence, For sure, Number is less than 40. Option is sufficient to answer the question.

As Option A is sufficient to answer the question, Answer Choices C, E are eliminated.

Case 2: N is 4 less than 4 times the units digit. Let's N is AB N=> 4*B-4 => 4*(B-1) So, B should be greater than 5. If B =5, N =4 (Invalid case) If B =6, N =8 (Invalid case) IF B =7, N =24 If B =8, N =28 If B =9, N =32. So, For sure Number is less than 40. Option is sufficient to answer the question.

So, Either statement is sufficient to answer this question.

Re: Is the positive two-digit integer N less than 40 ? [#permalink]

Show Tags

30 Dec 2012, 03:39

When considering statement 2, isn't 28 the only correct number?

When units digit is 8, \((4*units)-4 = (4*8)-4 = 32 - 4 = 28\)

The units digit of N=28 is also 8. So technically, N=24 or N=32 do not even satisfy the condition. But for DS, I guess (4*9)-4 is the fastest and best way. _________________

Re: Is the positive two-digit integer N less than 40 ? [#permalink]

Show Tags

30 Dec 2012, 06:58

Expert's post

th03 wrote:

When considering statement 2, isn't 28 the only correct number?

When units digit is 8, \((4*units)-4 = (4*8)-4 = 32 - 4 = 28\)

The units digit of N=28 is also 8. So technically, N=24 or N=32 do not even satisfy the condition. But for DS, I guess (4*9)-4 is the fastest and best way.

You are right: 28 is the only two-digit number which satisfies the second statement. _________________

Re: Is the positive two-digit integer N less than 40 ? [#permalink]

Show Tags

12 Jan 2014, 09:30

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________

Re: Is the positive two-digit integer N less than 40 ? [#permalink]

Show Tags

27 Jun 2014, 00:13

2

This post received KUDOS

Let no. be TU. (T- Ten's digit, U - Unit's digit). Also, since these are digits of a number & using the given constraint, 0<=U<=9, 1<=T<=9.

Required: 1<=T<=3 Constraints: 0<=U<=9, 1<=T<=9

A: U = T + 6 => T = U-6. Using constraints, U = 9,8,7; 1<=T<=9. This also results in 1<=T<=3. Hence, sufficient. B: 10T + U = 4U - 4 => T = (3U - 4)/10. Using constraints, U = 8; 1<=T<=9. This also results in 1<=T<=3. Hence, sufficient.

Re: Is the positive two-digit integer N less than 40 ? [#permalink]

Show Tags

23 Oct 2014, 03:49

umeshpatil wrote:

I solved it using method of substitution.

Given number(N) is 2 digit number. So, 0<N<100. So, Question is whether N<40

Case 1: If Number N is AB, AB => A (A+6). AB => 17,28,39. hence, For sure, Number is less than 40. Option is sufficient to answer the question.

As Option A is sufficient to answer the question, Answer Choices C, E are eliminated.

Case 2: N is 4 less than 4 times the units digit. Let's N is AB N=> 4*B-4 => 4*(B-1) So, B should be greater than 5. If B =5, N =4 (Invalid case) If B =6, N =8 (Invalid case) IF B =7, N =24 If B =8, N =28 If B =9, N =32. So, For sure Number is less than 40. Option is sufficient to answer the question.

So, Either statement is sufficient to answer this question.

B=5 --> N=4*(B-1) = 4*(5-1)= 16 valid case similarly B=6 --> N=4*(B-1) = 4*(6-1)= 20 valid case

just wanted to correct you.

this in no way changes the answer but might confuse someone. So just trying to help.

Re: Is the positive two-digit integer N less than 40 ? [#permalink]

Show Tags

10 Nov 2015, 04:14

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________

Re: Is the positive two-digit integer N less than 40 ? [#permalink]

Show Tags

15 Nov 2015, 01:44

Expert's post

1

This post was BOOKMARKED

Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

Is the positive two-digit integer N less than 40 ?

(1) The units digit of N is 6 more than the tens digit. (2) N is 4 less than 4 times the units digit.

There are 3 variables (n,a,b) and 1 equation (n=10a+b) in the original condition, 2 equations in the given conditions, making it likely that (C) will be our answer. Looking at the conditions, For 1, n=17,28,39<40 answers the question yes, and is therefore sufficient. For 2, 10a+b=4b-4, 10a+4=3b, and this answers the question 'yes' for n=28<40. This is sufficient as well, making the answer seem like (D). However, this is a logic question with commonly made mistake type 4(B).

Hence, (C) also becomes the answer but if we apply integer commonly made mistake type 4, the answer still becomes (D).

For cases where we need 2 more equation, such as original conditions with “2 variables”, or “3 variables and 1 equation”, or “4 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 70% chance that C is the answer, while E has 25% chance. These two are the majority. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since C is most likely to be the answer using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, D or E. _________________

Excellent posts dLo saw your blog too..!! Man .. you have got some writing skills. And Just to make an argument = You had such an amazing resume ; i am glad...

So Much $$$ Business school costs a lot. This is obvious, whether you are a full-ride scholarship student or are paying fully out-of-pocket. Aside from the (constantly rising)...

I barely remember taking decent rest in the last 60 hours. It’s been relentless with submissions, birthday celebration, exams, vacating the flat, meeting people before leaving and of...

Rishabh from Gyan one services, India had a one to one interview with me where I shared my experience at IMD till now. http://www.gyanone.com/blog/life-at-imd-interview-with-imd-mba/ ...