\[\boxed{\text{395\ (395).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\ a^{3} \cdot a = aaaa = a^{4}\]
\[\textbf{б)}\ a^{4} \cdot a^{2} = aaaaaa = a^{6}\]
\[\textbf{в)}\ a^{3} \cdot a^{6} = aaaaaaaaa = a^{9}\]
\[\textbf{г)}\ a^{20} \cdot a^{12} = a^{32}\]