Write the repeating decimal $0.\overline{515}$ as a fully simplified fraction.
The decimal fraction is: 0.515 515 515 515 ...
Let x = 0 . 515 515 515 515 ...
Then 1000x = 515 . 515 515 515 515 ...
Subtracting the first line from the second:
999x = 515
x = 515 / 999
