Ta có:
A = $\frac{-2.6^9+4^5.9^4}{6^8.20+3^8.2^{10}}$ + 0,(6)
= $\frac{-2.2^{9}.3^{9}+2^{10}.3^{8}}{2^{8}.3^{8}.20+3^{8}.2^{10}}$ +$\frac{2}{3}$
= $\frac{-2^{10}.3^{9}+2^{10}.3^{8}}{2^8.3^8.20+3^8.2^{10}}$ + $\frac{2}{3}$
= $\frac{2^8.3^8.(-4.3+4)}{2^8.3^8.(20+4)}$ + $\frac{2}{3}$
= $\frac{-8}{24}$ + $\frac{2}{3}$
= $\frac{-1}{3}$ +$\frac{2}{3}$
= $\frac{1}{3}$