16.
$$\eqalign{ & {\text{The value of}} \cr & {\log _5}\frac{{\left( {125} \right)\left( {625} \right)}}{{25}} \cr & {\text{is equal to - }} \cr} $$

17.
$$\eqalign{ & {\text{Determine the value of }} \cr & {\text{lo}}{{\text{g}}_{3\sqrt 2 }}\left( {\frac{1}{{18}}} \right)\,{\text{ is = ?}} \cr} $$

18.
$$\eqalign{ & {\text{The value of }} \cr & {\text{lo}}{{\text{g}}_{10}}\left( {0.0001} \right)\,\,{\text{is }} = ? \cr} $$

19.
$$\eqalign{ & {\text{What is the value of}} \cr & {\left[ {{\text{lo}}{{\text{g}}_{10}}\left( {{\text{5lo}}{{\text{g}}_{10}}100} \right)\,} \right]^2} = ? \cr} $$

20.
$${\text{If }}\,\,{\text{lo}}{{\text{g}}_8}{\text{p}} = 25\,\,{\text{and lo}}{{\text{g}}_2}{\text{q}} = 5\,,{\text{then - }}$$