$\frac{{13}^6\ast <!--\; \ast \; -->2^6}{{26}^5}=\frac{(13\ast <!--\; \ast \; -->2{)}^6}{{26}^5}=\frac{{26}^6}{{26}^5}=26$

$\frac{7^{11}\ast <!--\; \ast \; -->9^{11}}{({63}^5{)}^2}=\frac{(7\ast <!--\; \ast \; -->9{)}^{11}}{{63}^{10}}=\frac{{63}^{11}}{{63}^{10}}=63$

$\frac{2^8\ast <!--\; \ast \; -->3^8}{(6^4{)}^2}=\frac{(2\ast <!--\; \ast \; -->3{)}^8}{6^8}=\frac{6^8}{6^8}=1$

$\frac{{12}^6}{3^5\ast <!--\; \ast \; -->4^5}=\frac{{12}^6}{(3\ast <!--\; \ast \; -->4{)}^5}=\frac{{12}^6}{{12}^5}=12$