csat-suneung 2016 Q20

csat-suneung · South-Korea · csat__math-B 4 marks Laws of Logarithms Characteristic and Mantissa of Common Logarithms
For a positive number $x$, let $f ( x )$ be the characteristic (integer part) of $\log x$.
How many natural numbers $n$ not exceeding 100 satisfy $$f ( n + 10 ) = f ( n ) + 1$$ ? [4 points]
(1) 11
(2) 13
(3) 15
(4) 17
(5) 19
For a positive number $x$, let $f ( x )$ be the characteristic (integer part) of $\log x$.

How many natural numbers $n$ not exceeding 100 satisfy
$$f ( n + 10 ) = f ( n ) + 1$$
? [4 points]\\
(1) 11\\
(2) 13\\
(3) 15\\
(4) 17\\
(5) 19