Problem Solving

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

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

When the question stem includes the phrase which of the following, the correct answer choice is likely to be D or E.
Strategy:
Start with E.

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

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

The correct answer is E.

Remaining answer choices:

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.