\[\boxed{\text{445\ (445).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[a^{12} = \left( a^{3} \right)^{4} = \left( a^{2} \right)^{6} = \left( a^{4} \right)^{3} =\]
\[= \left( a^{6} \right)^{2}\]