Here's the general formula: (copy everything between angle brackets) <http://texify.com/?$\frac{1}{10^n-m} http://texify.com/?$\frac{1}{10^n-m} = \sum_{i=0}^\i

Here's the general formula: (copy everything between angle brackets) <http://texify.com/?$\frac{1}{10^n-m} http://texify.com/?$\frac{1}{10^n-m} = \sum_{i=0}^\infty \frac{m^i}{(10^n)^{i+1}}$> And here's OP's result where n=4 and m=2: http://www.wolframalpha.com/input/?i=%5Csum_%7Bi%3D0%7D%5E%5Cinfty+%5Cfrac%7B2%5Ei%7D%7B%2810%5E4%29%5E%7Bi%2B1%7D%7D http://www.wolframalpha.com/input/?i=%5Csum_%7Bi%3D0%7D%5E%5...