A bar over a sequence of digits in a decimal indicates that the sequence repeats indefinitely. What is the value of (10^4 - 10^2) (0.0012)?
Note: There is a bar over "12" in 0.0012. Couldn't figure out how to insert it.
(A) 0
(B) 0.12 (with the bar on 12)
(C) 1.2
(D) 10
(E) 12
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
A bar over
This topic has expert replies
-
GMATGuruNY
- GMAT Instructor
- Posts: 15539
- Joined: Tue May 25, 2010 12:04 pm
- Location: New York, NY
- Thanked: 13060 times
- Followed by:1906 members
- GMAT Score:790
The repeating digits beyond the bar represent values that are EXTREMELY SMALL relative to the other values.shahfahad wrote:A bar over a sequence of digits in a decimal indicates that the sequence repeats indefinitely. What is the value of (10^4 - 10^2) (0.0012)?
Note: There is a bar over "12" in 0.0012. Couldn't figure out how to insert it.
(A) 0
(B) 0.12 (with the bar on 12)
(C) 1.2
(D) 10
(E) 12
Thus, we can safely ignore the repeating digits beyond the bar.
(10� - 10²)(.0012)
= (10²)(10² - 1)(12/(10�)
≈ (10²)(10²)(12/10�)
= 12.
The correct answer is E.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
-
Matt@VeritasPrep
- 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
Another approach:
If xy is a two digit number (i.e. x = tens digit, y = units digit), then xy/99 = .xyxyxy...
We want this to be moved two places to the right, so we have xy/9900 = .00xyxyxy...
Hence .00121212... is 12/9900.
From there, we have (10� - 10²) * 12/9900, or 9900 * 12/9900, or 12.
If xy is a two digit number (i.e. x = tens digit, y = units digit), then xy/99 = .xyxyxy...
We want this to be moved two places to the right, so we have xy/9900 = .00xyxyxy...
Hence .00121212... is 12/9900.
From there, we have (10� - 10²) * 12/9900, or 9900 * 12/9900, or 12.
