Percentage+Number systems

[amanvij.1989]

Hi all ,
there are some questions bothering me on % and no. system please help me with these.....

Q1)16th% of 25?

Q2) Which of the following fraction is a terminating decimal?

a)19/91
b)17/225
c)12/231
d)41/256
e)35/324

any other method to calculate terminating no rather than division i know termination trend for 3,7 and 11

Will be posting more soon....

[jen]

Hi there,

This is Jennifer, MGRE instructor.

I'm not sure I understand your first question. Do you want one-sixteenth of one percent of 25? If so, (1/16)(1/100)(25) will give you the answer.

The second one, I have a very good trick for! Think about what types of fractions terminate as decimals and what types don't:

1/2 = 0.5 -> terminates
1/3 = 0.333333... -> doesn't
1/4 = 0.25 -> terminates
1/5 = 0.2 -> terminates
1/6 = 0.16666... -> doesn't

In short: if the denominator has only 2's and/or 5's in the denominator in fully reduced form, it'll terminate. If not, it won't.

Here are steps:
1) First, make sure you've fully reduced the fraction.
2) Make a prime tree for the denominator if needed. The numerator doesn't matter (as long as it's an integer).
3) If it's only 2's and/or 5's, it'll terminate. If not, it won't.

Choice D) will terminate because 256 is just 2^8.

Jen

[amanvij.1989]

Hey jen,
Thanks for this astounding info....i was solving it with the cal as i did'nt knew this logic will surely try this out.....

And for the 1st question even i was having same issue but your is right .

Thanks again for being such a support....

Tc

[tommywallach]

We are very very glad to help!

-t

P.S. You'd be surprised how rarely you need your calculator on the GRE, even though they provide it. Honestly, they did it more for the optics of it than the usage (they want the GRE to seem like a nice easy substitute for the GMAT). Keep it in mind when prepping!