Question 25
The function $f(n)$ is defined on the positive integers and takes non-negative integer values. It satisfies
(1) $f(m n) = f(m) + f(n)$,
(2) $f(n) = 0$ if the last digit of $n$ is $3$,
(3) $f(10) = 0$.
Find $f(1985)$.
(1) $f(m n) = f(m) + f(n)$,
(2) $f(n) = 0$ if the last digit of $n$ is $3$,
(3) $f(10) = 0$.
Find $f(1985)$.