Đáp án: C
Giải thích các bước giải:
$\begin{array}{l}
+ ){2^{1000}} = {2^{20.50}} = {\left( {{2^{20}}} \right)^{50}}\\
{2^{20}} \equiv 76\left( {\bmod 100} \right) \Rightarrow {2^{1000}} \equiv {76^{50}}\left( {\bmod 100} \right)\left( 1 \right)\\
+ ){76^{50}} = {76^{5.10}} = {\left( {{{76}^5}} \right)^{10}}\\
{76^5} \equiv 76\left( {\bmod 100} \right)\\
\Rightarrow {76^{50}} \equiv {76^{10}} = {\left( {{{76}^5}} \right)^2} \equiv {76^2} \equiv 76\left( {\bmod 100} \right)\left( 2 \right)\\
\left( 1 \right),\left( 2 \right) \Rightarrow {2^{1000}} \equiv 76\left( {\bmod 100} \right) \Rightarrow C
\end{array}$
