A6. We see that $\frac{1}{2}+\frac{1}{2^{2}}=\frac{3}{4}, \frac{1}{2}+\frac{1}{2^{2}}+\frac{1}{2^{3}}=\frac{7}{8}$ and $\frac{1}{2}+\frac{1}{2^{2}}+\frac{1}{2^{3}}+\frac{1}{2^{4}}=\frac{15}{16}$. What is $\frac{1}{2}+\frac{1}{2^{2}}+\frac{1}{2^{3}}+\frac{1}{2^{4}}+\frac{1}{2^{5}}+\frac{1}{2^{6}}+\frac{1}{2^{7}}+\frac{1}{2^{8}} ?$
(A) $\frac{1023}{1024}$
(B) $\frac{127}{128}$
(C) $\frac{255}{256}$
(D) $\frac{511}{512}$
(E) $\frac{1}{256}$
A6. In the search for the sum, the numerator is one less than the denominator. The denominator has the value of the highest power among the denominators of the addends on the left side of the expression.

## II. PART