Need a little help on this... Also posting my explanation along with it. 
Hi ddg,
I'd like to know a few things about this question before I offer a solution:
1) What is the source of this question? Did it come from a GMAT book/website/CAT/etc or did it come from a math book(or equivalent)?
2) As a problem solving question, it should include 5 answer choices. What are they?
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Number Theory - Factors
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Also, the answer is supposed to be 493
--------------------------------------------
Consider an example: 6 and 36 where 6 = n and 36 = n(square)
then 6 has the factors = 1, 2, 3, 6 (4 in number)
and 36 had the factors = 1, 2, 3, 4, 6, 9, 12, 18, 36 (9 in number)
Now any of the factors of 6 are < 6 and hence we subtract those numbers or remove those numbers from the factors of n(square) -> we get 4, 9, 12, 18, 36 left.
Out of all of these factors, only 4 is < 6 that does NOT divide (specified according to qn to find factors < n that don't divide n).
So in an example such as this, we have only one factor.
Now considering that for this qn, n(square) has 59X35 factors = 2065 factors.
And n has 540 factors. So, subtracting them, the pool of factors we can choose from is = 2065 - 540 = 1525 factors. how do we know how many of these factors are less than n???????
--------------------------------------------
Consider an example: 6 and 36 where 6 = n and 36 = n(square)
then 6 has the factors = 1, 2, 3, 6 (4 in number)
and 36 had the factors = 1, 2, 3, 4, 6, 9, 12, 18, 36 (9 in number)
Now any of the factors of 6 are < 6 and hence we subtract those numbers or remove those numbers from the factors of n(square) -> we get 4, 9, 12, 18, 36 left.
Out of all of these factors, only 4 is < 6 that does NOT divide (specified according to qn to find factors < n that don't divide n).
So in an example such as this, we have only one factor.
Now considering that for this qn, n(square) has 59X35 factors = 2065 factors.
And n has 540 factors. So, subtracting them, the pool of factors we can choose from is = 2065 - 540 = 1525 factors. how do we know how many of these factors are less than n???????
