\[\boxed{\mathbf{245}.}\]
\[36^{24} + 21^{45} + 7^{8} =\]
\[= (3 \cdot 10 + 6)^{24} +\]
\[+ (2 \cdot 10 + 1)^{45} + 7^{8} =\]
\[= 10 \cdot n + 6^{24} + 1^{45} + 7^{8}\]
\[6^{1} = 6;\ \ 6^{2} = 36 - повтор;\]
\[6^{24}\ :10 = a\ (ост.\ 6).\]
\[1^{1} = 1;\ \ 1^{2} = 1 - повтор;\]
\[1^{45}\ :10 = a\ (ост.\ 1).\]
\[7^{1} = 7;\ \ 7^{2} = 49;\ \ 7^{3} = 243;\]
\[\text{\ \ }7^{4} = 2401;\]
\[7^{5} = 16\ 087 - повтор;\ \]
\[8\ :4 = 2\ (ост.\ 0) \rightarrow 7^{0} = 1.\]
\[Остаток\ от\ деления:\]
\[6 + 1 + 1 = 8.\]
\[Ответ:8.\]