What is the number of terms in this series $1+0.5+0.25+\ldots+0.5^{n−1}$? And what is the sum? 
What is the number of terms in this series $1+0.5+0.25+\ldots+0.5^{n−1}$? And what is the sum?

I stumped by this question, but have a feeling the answer's really obvious:S
Am I supposed to get an actual number as the answer?
Thanks for the help!

use the geometric series 
$$\frac{1}{1-x}=1+x+x^2+x^3+.....x^n$$
$$\frac{1}{1-x}-1=x+x^2+x^3+.....x^n$$
$$\frac{1}{1-x}-1=x(1+x+x^2+x^3+.....x^{n-1})$$
$$\frac{x}{1-x}=x(1+x+x^2+x^3+.....x^{n-1})$$
hence
$$\frac{1}{1-x}=(1+x+x^2+x^3+.....x^{n-1})$$
$|x|<1$
plug $x=0.5$
$$\frac{1}{1-0.5}=2$$
