Solution
= Solution
This <geometric series> has first term $2^{-4}=1/16$ and common ratio $1/2$, whose <absolute value> is less than one. Consequently
$$
\boxed{\sum_{n=4}^\infty2^{-n}=\frac{1/16}{1-1/2}=\frac18.}
$$
= Solution
This <geometric series> has first term $2^{-4}=1/16$ and common ratio $1/2$, whose <absolute value> is less than one. Consequently
$$
\boxed{\sum_{n=4}^\infty2^{-n}=\frac{1/16}{1-1/2}=\frac18.}
$$