Source: Official Guide for GMAT Review 2016 Problem Solving; #174


A bar over a sequence of digits

A bar over a sequence of digits in a decimal indicates that the sequence repeats indefinitely. What is the value of (10-10)(0.0012)?

1 Explanation


Gravatar Mike McGarry, Magoosh Tutor

Aug 17, 2015 • Comment

Rafael Martinez

Hey I think that you accidentally zoomed in too much on the video for this response. Also, I have a question. Could you do this with a difference of perfect squares? (10^2-10)*(10^2+10)*(.0012) and then you get 90(110)(.0012) = 9900*.0012 = around 11.88?

Aug 19, 2016 • Reply

Cydney Seigerman, Magoosh Tutor

Hi Rafael,

Thanks for letting us know about the video zoom! Since we're a small team with a lot of projects going on, it might be a while until we fix this issue, but it's on our radar :)

In terms of your question, your method does work and you will get the right answer by rounding your approximation up to 12. Also, if you multiply 0.001212... by 9900, the product is 12. However, this is not the best approach in this case, mainly because the multiplication is a bit time-consuming.

Hope this helps :)

Aug 29, 2016 • Reply

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Official Guide for GMAT Review 2016

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Section 5.3 Problem Solving

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