\[\boxed{\mathbf{14}.}\]
\[1)\ \frac{a^{2} \cdot a^{- 5}}{a^{3}} = \frac{a^{- 3}}{a^{3}} = a^{- 6}\]
\[2)\ \frac{- b^{4} \cdot b^{8}}{b^{6}} = \frac{b^{4}}{b^{6}} = b^{- 2}\]
\[3)\ a^{- 6}b^{3} = \left( a^{- 2}b \right)^{3}\]
\[4)\ c^{- 5}d^{- 10} = \left( cd^{2} \right)^{- 5}\]