Ta có :
\(5^6\equiv1\left(mol7\right)\)
\(\Rightarrow\left(5^6\right)^{335}\equiv1^{335}\left(mol7\right)\)
\(\Rightarrow5^{2010}\equiv1\left(mol7\right)\)
\(\Rightarrow5^{2010}.5^3=1.5^3\left(mol7\right)\)
\(\Rightarrow5^{2013}=125\left(mol7\right)\)
Mà : \(125\equiv6\left(mol7\right)\)
\(\Rightarrow5^{2013}\equiv6\left(mol7\right)\)
Vậy \(5^{2013}\) chia 7 dư 6