How to tackle this?
I would first check what is the greates common factor o 18 and 30. It is 6. So each side of the square would be 6 inches. The area you have to cover is 540 (18 x 30). You can thus cut out 15 squares of 6x6 inches.
I got 15 is it correct?
I took H.C.F of both.
18 and 30. which is 6. So it will be the side of the square. so there will be total 15 squares which can be made if we consider the rectangle.
Please let me know the answer if I am wrong.
is it B and C?
How did you know that you needed to find the greatest common factor and not lcm?
yup,
can you explain how you got option c?
that wouldn’t make any sense. How could you have a square of 90x90 in a 18x30 rectangle?
Think of it conceptually. What is the first square you can try? You can fit multiple squares of 1x1 inches. But also squares of 2x2 inches. And since you have to find the least possible number, the square should be as big as possible. So keep going. 3x3 is equally possible. 4x4, 5x5 is not possible (18 is not divisible by them) but 6x6 is…
ok thanks, got it
Now its clear
Like this is the way I thought.
Here the question says “must be true” so it should work for all cases.
all the variables are positive integers.
Suppose,
a = 37 , b=1
ab = 37
c+d = 10
in this c+d is even now if c is even then d must be even.
Like c = 2 then d = 8.
or say c = 4 then d =6,etc.
now take
a = 37 , b =2
ab = 37 * 2
c+d = 20
in this c+d is even now if c is even then d must be even.
Like c = 12 then d = 8.
or say c = 2 then d =18.
This you can try with different values of ab and (c+d) which satisfies the question.
Nicely explained
Thanks a lot
Here’s how i did it: Multiply 18 and 30 that equals 540.
Then divide 540 by the answer choices and look for a perfect square. The only one that works is (E)
nice trick
nice trick 
How can I extract the most value from the 5lb book quant section? Any tips regarding this book usage?
even, I am not sure.
I find around 3-4 question, in each chapter, which I am not able to solve.
Do you solve chapter questions in one go? I get tired easily when there are 40 questions in a chapter so I break them into 20 questions for each section.
You should be happy that you can solve the majority of those questions. I don’t get upset when I attempt a question wrong because difficulty in those questions is quite high than in the real GRE exam. If you can’t attempt only 2-3 questions in the chapter, your quant score on the ETS will be above 165.
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I try to solve all the questions in one go if the chapter contains around 40-50 questions, otherwise, I would also divide them.
I try to solve the set of 40 questions in 40 minutes, but It usually takes me 45-50 minutes.
That’s how I do it, but I do this after completing all my other work because after solving the set, I don’t feel like doing anything.
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