46.
$$\eqalign{ & {\text{The number of digits in }}{{\text{4}}^9} \times {{\text{5}}^{17}}{\text{,}} \cr & {\text{when expressed in usual form, is - }} \cr} $$

47.
$$\eqalign{ & {\text{If}}\,\log 3\log \left( {{3^x} - 2} \right)\,{\text{and}}\,\log \left( {{3^x} + 4} \right)\, \cr & {\text{are}}\,{\text{in}}\,{\text{arithmetic}}\,\,{\text{progression}}\,{\text{,}} \cr & {\text{then}}\,x\,{\text{is}}\,{\text{equal}}\,{\text{to}} - \cr} $$

48.
$$\eqalign{ & {\text{If}}\,{\log _{10}}a = p,\,\,\,{\log _{10}}b = q, \cr & {\text{then}}\,{\text{what}}\,\,{\text{is}}\,\,{\log _{10}}\left( {{a^p}{b^q}} \right)\,\,{\text{equal}}\,\,{\text{to}}? \cr} $$