Answer:
\(S=\left(1+5^2+5^4+5^6\right)+...+\left(5^{2014}+5^{2016}+5^{2018}+5^{2020}\right)\)
\(=\left(1+5^2+5^4+5^6\right)+...+5^{2014}+\left(1+5^2+5^4+5^6\right)\)
\(=\left(1+5^2+5^4+5^6\right).\left(1+...+5^{2014}\right)\)
\(=16276.\left(1+5^2+...+5^{2014}\right)⋮313\)
Mà ta có: \(S=16276⋮313\)
Vậy \(S⋮313\)