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

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

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

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

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