Question

1 upon 5+1 upon 5 square 2 +1 upon 5 square 3+1 upon 5 square four = to answer

Answer 1

$\frac{1}{5} + \frac{1}{5 {}^{2} } + \frac{1}{5 {}^{3} } + \frac{1}{5 {?}^{4} }$