\(\dfrac{81^4.3^{10}.27^5.3^{12}}{3^{18}.9^3.243^2}\)
=\(\dfrac{\left(3^4\right)^4.3^{10}.\left(3^3\right)^5.3^{12}}{3^{18}.\left(3^2\right)^3.\left(3^5\right)^2}\)
= \(\dfrac{3^{16}.3^{10}.3^{15}.3^{12}}{3^{18}.3^6.3^{10}}\)
\(=\dfrac{3^{53}}{3^{34}}\)
= \(3^{19}\)