You are given two $10$-based integers $b$ and $x$, and you are required to determine the following proposition is true or false:
For arbitrary $b$-based positive integer $y = \overline{c_1 c_2 \cdots c_n}$ ($c_i$ is the $i$-th dight from left of $y$), define $\displaystyle f(y) = \sum_{i=1}^n c_i$, if $\underbrace{f( f( \cdots f(y) \cdots ))}_{\infty}$ can be divided by $x$, then $y$ can be divided by $x$, otherwise $y$ can't be divided by $x$.