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can you please tell, when should one look at the option choices, I avoid looking at them before I derive the solution myself, often it is wrong and at the testing conditions it makes me panic when I see that my answer is not the listed one.. in such case I pick the one which is closest to mine answer..which is more often wrong approach..

when should I consider OPTION CHOICES in order to derive the at the solution ... can you also share a link to GRE MATHS STRATEGIES.

How many different two-digit positive integers are there in which the tens digit is greater than 6 and the units digit is less than 4 ?

A) 7

B) 9

C) 10

D) 12

E) 24

If the tens digit is greater than 6, there are 3 options (7, 8, 9) for the tens digit. If the units digit is less than 4, there are 4 options (3, 2, 1, 0) for the units digit, so we have a total of 3 x 4 = 12 ways to create the number.

Answer: D
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Re: How many different two-digit positive integers are there in [#permalink]
22 Jan 2019, 06:39

1

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Expert's post

IshanGre wrote:

can you please tell, when should one look at the option choices, I avoid looking at them before I derive the solution myself, often it is wrong and at the testing conditions it makes me panic when I see that my answer is not the listed one.. in such case I pick the one which is closest to mine answer..which is more often wrong approach..

when should I consider OPTION CHOICES in order to derive the at the solution ... can you also share a link to GRE MATHS STRATEGIES.

Thanks in advance.

You should ALWAYS check the answer choices BEFORE performing any calculations. There are many reasons for this (see video below), but here's a rudimentary example:

Let's say you have a counting question, and you recognize that the answer will equal 26^3 Let's also say the answer choices are: A) 17,572 B) 17,573 C) 17,574 D) 17,575 E) 17,576

If we try head straight to the online calculator (or start multiplying 26x26x26 on scratch paper), we're missing out on a 1-second answer.

Since all powers of 26 will have 6 as a units digit, we know that the correct answer is E

For more on this, watch:

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Re: How many different two-digit positive integers are there in [#permalink]
02 Feb 2019, 00:59

I have a big question regarding the concept of this question. I am looking at some questions involving integers that are not considering 0 as a positive integer. Here is an example from Barrons Model paper test 2:

Q. A number x is chosen at random from the set of integers less than 10. What is the probability that 9/x > x?

I considered 0 as a positive integer and got 3/10. But the explanation does not consider 0 and the correct answer is 2/9.