Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
A and C are out because the denominators aren't even.
Left with BDE
D is 5^2 / 12^2, since 5/12 isn't a terminating decimal, I suppose the square of them aren't too.
D is out
It's E, because the denominator is a multiple of 2. (But I'm not sure, because my approach is rather unsustained. However, I guess there is no number which, if divided by 2 or a multiple of it, yields an non-terminating decimal.)
( 196 is the square of the odd number 3; I think the division by an odd number ( I used this approach also above) yields an non-terminating decimal.)
Lets look at each fraction
a. 10/189=10*1/(3^3)*1/7 each of this simpe fractions does not lead to derminating decimal
b.15/195=15*1/13*1/13 the same thing
c. 16/225 = 16*1/5*1/5*1/9 no
d. 25/144=25*1/(3^2)*1/(2^4) 1/3 is present and does not give determinating decimal
e. 39/128=39/(2^7) Yes. 1/2 =0.5 and (0.5)^7 has the end.