41.
If $${\log _7}{\log _5}\left( {\sqrt {x + 5} + \sqrt x } \right)$$     $$ = 0,$$  what is the value of x ?

42.
If $${\text{a}} = {\text{lo}}{{\text{g}}_{\text{8}}}\,{\text{225}}$$   and $${\text{b = lo}}{{\text{g}}_{\text{2}}}\,{\text{15}},$$   then a in terms of b is -

43.
If $$\log 2 = 0.3010\,$$   and $$\log 3 = 0.4771,\,$$   the value of $${\log _5}512$$   = ?

44.
If the logarithm of a number is - 3.153, what are characteristic and mantissa?

45.
If $$\log 2 = 0.30103,$$    the number of digits in $${4^{50}}$$ is -