Gmat prep ques 1

[abhinav85]

The value of 10^8-10^2/10^7-10^3 is closest to which of the following?

A) 1

B) 10

C) 10^2

D) 10^3

E) 10^4

B

[kvamsy]

I have got B as answer as below

10^2(10^6-1) (10^2)^3) - 1
---------------- ------> ---------------- *1/10
10^3(10^4-1) (10^2)^2 - 1

Expanding as A^3-B^3 and A^2 - B^2

Gives us 10101/1010 gives 10 as answer


Hope i am right

[sacx]

If you are subtracting a very small number from a comparatively bigger number then the resulting number is very near to the bigger number.

So your question would effectively convert into 10^8/10^7 equals to what??

and the answer to that is simple 10

B

[pathaniaus]

hmm i tried solving that on my own... I got 10^2. I do not know where i am making my mistake. Could you please explain in detail?

[cata1yst]

hmm i tried solving that on my own... I got 10^2. I do not know where i am making my mistake. Could you please explain in detail?

Here is what I did. Try this...

(10^8 - 10^2) / (10^7 - 10^3)

Factor out 10^2 on both the top and bottom of the fraction.

[ 10^2 * (10^6 - 1) ] / [ 10^2 * (10^5 - 10) ]

You can now cancel out 10^2 and you are left with...

(10^6 - 1) / (10^5 -10)

Which is basically...

10^6 / 10^5 = 10