TERMINATING DECIMAL

pappueshwar wrote:Which of the following fractions has a decimal equivalent that is a terminating decimal?

A. 10/189
B. 15/196
C. 16/225
D. 25/144
E. 39/ 128

IS THERE AN EASY WAY TO SOLVE. OA IS E

For a fraction to yield a terminating decimal, its denominator must be composed ONLY of powers of 2 and/or of powers of 5 when the fraction is in its MOST REDUCED FORM.

In any multiple of 3, the sum of the digits is a multiple of 3.
Thus, the denominators of A (189), C (225), and D (144) are all multiples of 3.
None of these answer choices can be further reduced.
Since each of these answer choices is in its most reduced form, and each has in its denominator something other than a power of 2 or a power of 5, none will yield a terminating decimal.
Eliminate A, C and D.

Answer choice B: 15/196 = (3*5)/(2*2*7*7)
Since in its most reduced form this fraction has in its denominator something other than a power of 2 or a power of 5, the resulting decimal will not be terminating.
Eliminate B.

The correct answer is E.

Answer choice E: 39/128 = (3*13)/(2^7).
Since in its most reduced form this fraction has in its denominator only a power of 2, the resulting decimal will be terminating.

Is this GMAT material?

Yes it is but i took from a different website.

pappueshwar wrote:Which of the following fractions has a decimal equivalent that is a terminating decimal?

A. 10/189
B. 15/196
C. 16/225
D. 25/144
E. 39/ 128

A decimal will terminate when the equivalent fraction in lowest terms has a denominator that breaks down to primes of 2’s only, 5’s only, or both 2’s and 5’s only.

Looking at our answer choices we see that 39/128 is a terminating decimal since 128 = 2^7.

Answer: E