If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

# GMAT: Math 4

20-23, pgs. 154-155. Created by Sal Khan.

## Want to join the conversation?

• #33. ( I don't have text of the book, so correct me if I misunderstood something) Shouldn't it be (7;5) since the vertical axis is depicted downwards? I mean we were taught that numbers on the line increase from the cross in the direction of the axis, so now I'm confused with the question • In quadrant I, (X,Y) X and Y are both positive. In quadrant II, (-X,Y) X is negative and Y is positive. In quadrant III, (-X,-Y) X and Y are both negative. In quadrant IV, (X,-Y) X is positive and Y is negative. Coordinates of V is in quadrant IV, (X,-Y) V = (7,-5). Y going above 0 is going to be positive and Y going below 0 is going to be negative. I think the arrow is what confuses you, disregard the arrow going in the down direction and answer by which quadrant the coordinate is placed. V is on quadrant IV.
• As I look at the book... The answer is (A) -2, because the point on the number line associated with E is not quite pointing at 2, somewhere between 1 and 2. The point on the number line associated with A is clearly pointing at -2. Look closely :) • If there was more than seventy two numbers (20) or seventy one, and the (for the seventy one) what will it happen if the number to find is in the middle of it?
Show me a example or a tell me a reason. • Time Question 22.
Is there a trick to doing this question that isn't covered in this video. If one has to do that much long division in the exam it would really waste time. At an average of around 2 minutes per question, this would be really tough to squeeze in!
Any help on tricks or methods for this kind of question would be appreciated!
(1 vote) • Well, working with numbers a lot tends to help. Two options are clearly off the table because we hopefully know that the repeating pattern resulting when dividing by 3 is every number (1/3 and 2/3). Dividing by 9s is famous for being every number repeated, such as 8/9 is 0.88888...
I was just doing some math dividing by 11, so I found it interesting that it alternated: 2/11 is 0.181818...
3/11 is 0.272727
By logic then, I guessed that the 41/99 was going to be alternating pattern of two digits because a divisor of 99 is actually dividing by 9 x 11. And, in fact it is the numerator repeated, which is kind of cool: 41/99 is 0.41414141
8/99 is 0.080808
So that leaves the last possibility by process of elimination.
One other thing I know from working a lot with numbers is that numbers ending in 7 as a divisor tend to be messy. So that helps confirm that 23/37 is a good choice. Then, if you feel you need to make sure, as a last resort you can DIVIDE it.

Indeed it ends up 0.621 621 621

If you ever are given this question with an option divided by 7, choose that one.
58/7 = 8.285714 285714 which is a reliable l-o-n-g repeat
10/7 = 1.428571 428571
39/7 = 5.571428 571428
16/7 = 2.285714 285714 hmmm, like 58
All of them contain the same sequence of numbers, but start at different places in the sequence, depending on what (oh well, you don't need to know WHY, only that there is a long repeat)

It helps to know the divisibility rules also, and practicing long division before a test like this can make sure you don't trip on the mechanics if you cannot find a way to eliminate the alternatives.
• Are gmat questions this easy ? • Is this test for high school students or younger?
(1 vote) • Which book (edition) is being used here?
(1 vote) • where can I get the pdf material from the questions being resolved in here ? Thanks
(1 vote) • Vote for me
and math is hard for thanks for this series
(1 vote) • what is the name of the book your using for question I would like to purchase so I can follow along
(1 vote) 