Division

This topic has expert replies
Source: — Problem Solving |

User avatar
Legendary Member
Posts: 682
Joined: Fri Jan 16, 2009 2:40 am
Thanked: 32 times
Followed by:1 members

Re: Division

by Vemuri » Tue May 05, 2009 6:25 am
dtweah wrote:Which of the following is the quotient of (2^9 +3^9)/35

A. 521
B. 560
C. 577
D. 627
E. 842
B-) Good one. I am sure there should be a easy way to solve this problem. I gave it just 2 mins & solved it manually to get C as the answer.

Master | Next Rank: 500 Posts
Posts: 487
Joined: Fri Mar 27, 2009 5:49 am
Thanked: 36 times

Re: Division

by dtweah » Tue May 05, 2009 7:51 am
Vemuri wrote:
dtweah wrote:Which of the following is the quotient of (2^9 +3^9)/35

A. 521
B. 560
C. 577
D. 627
E. 842
B-) Good one. I am sure there should be a easy way to solve this problem. I gave it just 2 mins & solved it manually to get C as the answer.
You bet there is. Trying solving it that way. Mind you the numbers could be a little bigger on the GMAT. It can be solved in under one min.

Master | Next Rank: 500 Posts
Posts: 148
Joined: Wed Dec 10, 2008 5:13 pm
Location: SF, CA
Thanked: 12 times

Re: Division

by lilu » Tue May 05, 2009 9:14 am
dtweah wrote:
Vemuri wrote:
dtweah wrote:Which of the following is the quotient of (2^9 +3^9)/35

A. 521
B. 560
C. 577
D. 627
E. 842
B-) Good one. I am sure there should be a easy way to solve this problem. I gave it just 2 mins & solved it manually to get C as the answer.
You bet there is. Trying solving it that way. Mind you the numbers could be a little bigger on the GMAT. It can be solved in under one min.
Can you please let everyone one know about this method?
First, I thought we should use the fact that 2^9 is a small number when compared to 3^9 and ignore it, but answer choices are so close together that this method will definitely not work.
The more you look, the more you see.

Master | Next Rank: 500 Posts
Posts: 487
Joined: Fri Mar 27, 2009 5:49 am
Thanked: 36 times

Re: Division

by dtweah » Tue May 05, 2009 10:51 am
lilu wrote:
dtweah wrote:
Vemuri wrote:
dtweah wrote:Which of the following is the quotient of (2^9 +3^9)/35

A. 521
B. 560
C. 577
D. 627
E. 842
B-) Good one. I am sure there should be a easy way to solve this problem. I gave it just 2 mins & solved it manually to get C as the answer.
You bet there is. Trying solving it that way. Mind you the numbers could be a little bigger on the GMAT. It can be solved in under one min.
Can you please let everyone one know about this method?
First, I thought we should use the fact that 2^9 is a small number when compared to 3^9 and ignore it, but answer choices are so close together that this method will definitely not work.

(2^3)^3 +(3^3)^3= (2^3 +3^3) ((2^3)^2 -(2^3) (3^3) +(3^3)^2)
RHS is 35 x 577
Sum of cubes. Watch out for sum and difference of cubes.