Last visit was: 14 Jul 2024, 10:36 It is currently 14 Jul 2024, 10:36
Toolkit
GMAT Club Daily Prep
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

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.

# The three digits of a number add up to 11. The number is div

SORT BY:
Tags:
Show Tags
Hide Tags
Manager
Joined: 10 Jul 2013
Posts: 228
Own Kudos [?]: 1049 [8]
Given Kudos: 102
Verbal Forum Moderator
Joined: 10 Oct 2012
Posts: 485
Own Kudos [?]: 3135 [4]
Given Kudos: 141
Senior Manager
Joined: 24 Aug 2009
Posts: 388
Own Kudos [?]: 2292 [0]
Given Kudos: 276
Concentration: Finance
Schools:Harvard, Columbia, Stern, Booth, LSB,
Math Expert
Joined: 02 Sep 2009
Posts: 94342
Own Kudos [?]: 640754 [2]
Given Kudos: 85011
Re: The three digits of a number add up to 11. The number is div [#permalink]
1
Kudos
1
Bookmarks
Asifpirlo wrote:
The three digits of a number add up to 11. The number is divisible by 5. The leftmost digit is double the middle digit. What is the product of the three digits?

A. 40
B. 72
C. 78
D. 88
E. 125

Say the three-digit number is abc.

The leftmost digit is double the middle digit --> a=2b;
The number is divisible by 5 --> c is either 0 or 5;
The three digits of a number add up to 11 --> a+b+c=11

So, either a+b+c=2b+b+0=11 or a+b+c=2b+b+5=11. The first equation does not give an integer value of b, so it's not the case. From the second we get that b=2 --> a=4 and c=5 --> a*b*c=40.

Senior Manager
Joined: 07 Apr 2014
Status:Math is psycho-logical
Posts: 335
Own Kudos [?]: 393 [1]
Given Kudos: 169
Location: Netherlands
GMAT Date: 02-11-2015
WE:Psychology and Counseling (Other)
The three digits of a number add up to 11. The number is div [#permalink]
1
Kudos
Since the sum is 11, it is really easy to try some values.

The last one is 0 or 5.
The first one is twice the second one.

So,
First one: 2
Second one: 1
Third one: 8, doesn't work

First one: 3
Second one: 6
Third one: 2, doesn't work

First one: 4
Second one: 2
Thirdd one: 5, works

There is no way you can have 0 as the last digit, because you cannot have anything more than 4 as the first digit.

So, 4*2*5 = 40 ANS A

Originally posted by pacifist85 on 11 Jan 2015, 07:38.
Last edited by pacifist85 on 11 Jan 2015, 23:24, edited 1 time in total.
Manager
Joined: 01 Feb 2012
Posts: 80
Own Kudos [?]: 137 [0]
Given Kudos: 151
Re: The three digits of a number add up to 11. The number is div [#permalink]
We can also solve this by estimating the answer with the help of answer choices if we can't figure out the correct way which Bunuel and others already suggested....

It is a 3 digit no. say abc and divisible by 5 so C has to be either 0 or 5.
Now a=2b so number can be written as 2b*b*0 or 2b*b*5. In either case the last digit of the number will be 0 because 0 multiplied by anything gives 0 and 5*2*anything will also give last digit 0.
There is only one answer with last digit as 0 which is A.

Asifpirlo wrote:
The three digits of a number add up to 11. The number is divisible by 5. The leftmost digit is double the middle digit. What is the product of the three digits?

A. 40
B. 72
C. 78
D. 88
E. 125
GMAT Club Legend
Joined: 19 Dec 2014
Status:GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Posts: 21835
Own Kudos [?]: 11778 [0]
Given Kudos: 450
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: The three digits of a number add up to 11. The number is div [#permalink]
Hi All,

When a question has a limited number of possibilities, you can sometimes "brute-force" your way to the solution.

Here, we have a bunch of facts to work with:
1) A 3-digit number
2) Digits add up to 11
3) Number is evenly divisible by 5 (so it ends in 0 or 5)
4) The first digit is double the second digit.

Starting with the last fact, we only have a four options:
21_
42_
63_
84_

If you plug 0 in for the last digit, you WON'T end up with a sum of 11, so the last digit MUST be a 5 and the only possible 3-digt number is...

425

GMAT assassins aren't born, they're made,
Rich
Non-Human User
Joined: 09 Sep 2013
Posts: 33966
Own Kudos [?]: 851 [0]
Given Kudos: 0
Re: The three digits of a number add up to 11. The number is div [#permalink]
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: The three digits of a number add up to 11. The number is div [#permalink]
Moderator:
Math Expert
94342 posts