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

Redeem

Questions on base system

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Quantitative Reasoning |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Sun Jul 10, 2016 4:26 am
Abhey Kharbanda wrote:Hi guys, does the GMAT ask questions on base system?

For example: how would you write 2234 in base 4 to a number in base 7?
That kind of question would be out of scope for the GMAT.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pm
Location: Palo Alto, CA
Thanked: 2867 times
Followed by:511 members
GMAT Score:800

by [email protected] » Sun Jul 10, 2016 5:25 am
Hi Abhey Kharbanda,

All of the questions that you'll face on the Official GMAT are in base-10, so you won't have to worry about working in any other base. That's a rather interesting question to be asking - have you been working with practice materials that expected you to convert your math to a different base?

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
User avatar
Newbie | Next Rank: 10 Posts
Posts: 2
Joined: Sat Jul 09, 2016 11:41 pm

by Abhey Kharbanda » Mon Jul 11, 2016 12:51 am
[email protected] wrote:Hi Abhey Kharbanda,

All of the questions that you'll face on the Official GMAT are in base-10, so you won't have to worry about working in any other base. That's a rather interesting question to be asking - have you been working with practice materials that expected you to convert your math to a different base?

GMAT assassins aren't born, they're made,
Rich
Thanks Rich, no I haven't been working on them but thought of asking it here
Top
Master | Next Rank: 500 Posts
Posts: 199
Joined: Sat Apr 26, 2014 10:53 am
Thanked: 16 times
Followed by:4 members
GMAT Score:780

by 800_or_bust » Tue Jul 12, 2016 6:10 am
Abhey Kharbanda wrote:Hi guys, does the GMAT ask questions on base system?

For example: how would you write 2234 in base 4 to a number in base 7?
2234 in base 4

(2 x 4^3) + (2 x 4^2) + (2 x 4) + 4 = 128 + 32 + 8 + 4 = 172 (Base 10)

In Base 7... Wasn't sure how to do this formulaically, so I just logically reasoned it out.

172 (Base 10) = (3 x 7^2) + (3 x 7) + 4 = 334 (Base 7)
800 or bust!
Top
Master | Next Rank: 500 Posts
Posts: 416
Joined: Thu Oct 15, 2009 11:52 am
Thanked: 27 times

by regor60 » Wed Jul 13, 2016 7:39 am
Can't have a "4" in base 4, etcetera.

The base number is always written as 10 in the base system
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 410
Joined: Fri Mar 13, 2015 3:36 am
Location: Worldwide
Thanked: 120 times
Followed by:8 members
GMAT Score:770

by OptimusPrep » Sun Jul 17, 2016 8:37 pm
Abhey Kharbanda wrote:Hi guys, does the GMAT ask questions on base system?

For example: how would you write 2234 in base 4 to a number in base 7?
Fortunately no.
And even if you are asked one, you would be told in the question itself how to change from one base to another and then the question would be asked.
Top
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Fri Jul 22, 2016 1:31 am
edit
Last edited by Matt@VeritasPrep on Fri Apr 28, 2017 12:41 am, edited 1 time in total.
Top
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Fri Jul 22, 2016 1:35 am
800_or_bust wrote:
2234 in base 4

(2 x 4^3) + (2 x 4^2) + (2 x 4) + 4 = 128 + 32 + 8 + 4 = 172 (Base 10)

In Base 7... Wasn't sure how to do this formulaically, so I just logically reasoned it out.

172 (Base 10) = (3 x 7^2) + (3 x 7) + 4 = 334 (Base 7)
There are a couple errors here, but the idea is right! Some bases are easier to convert than others (i.e. you don't really have to run them through base 10), but I don't see an obvious way of doing 4 to 7 directly.
Top
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Fri Nov 11, 2016 1:42 pm
Should of course add explicitly again that BASE SYSTEMS ARE NOT TESTED ON THE GMAT AS OF 2016.
Top
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Fri Nov 11, 2016 1:42 pm
... which is a shame, because they're great fun (hint hint, GMAC! :))
Top
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Wed Mar 15, 2017 4:48 pm
Matt@VeritasPrep wrote:... which is a shame, because they're great fun (hint hint, GMAC! :))
Still holding out hope for these in GMAT 2017 ...
Top
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Wed Mar 15, 2017 4:49 pm
... though the newer inequalities and quadratics and whatever else are cool too :)
Top
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Thu May 11, 2017 8:00 pm
There isn't any base system on the GMAT (yet!), but it does appear on the Indian CAT.

And just for fun, 2234 isn't a number in base 4, since base 4 only has the digits 0, 1, 2, and 3. That said, suppose we have 2233 in base 4, and we want to convert it to base 7. We know that

2233(base 4) = 2*4³ + 2*4² + 3*4¹ + 3 => 175(base 10)

Now we want to put 175 in base 7. We start with the highest power of 7 that has a multiple less than 175: in this case, 7², which has the multiple 3*7². 175 - 3*7² = 28, so we have 28 left over. 28 = 4*7¹, so we're set:

175(base 10) = 3*7² + 4*7¹ + 0 => 340(base 7)
Top
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Thu May 11, 2017 8:03 pm
We also could try something like this:

2233 (base 4) =>

2000 + 200 + 30 + 3 (base 4) =>

2*1000 + 2*100 + 3*10 + 3 (base 4)

Since 10� (base 4) = 4� (base 10), we can replace 1000 with 4³, 100 with 10², etc.
Top
Post new topic Post Reply
• Page 1 of 1