sabxu1 wrote:

Bunuel wrote:

SOLUTION

\(\frac{31}{125} =\)

(A) 0.248

(B) 0.252

(C) 0.284

(D) 0.312

(E) 0.320

\(\frac{31}{125} =\frac{31*8}{125*8} =\frac{248}{1000} =0.248\).

Answer: A.

why do you choose to times by 8?

Since the options are all in the decimal forms, we need to divide the numerator by denominator.

If we have a calculator, we can directly divide it. But since we are not allowed a calculator, we need to make our lives simpler.

Hence we try to bring denominator in a form by which the division becomes easier.

125 = 5^3

If we multiply 5^3 by 2^3, we get 10^3 or 1000 and then we can easily divide.

Hope this clarifies your doubt.