Extracting All Digits

You can extract all digits by repeating the process: take $n \bmod 10$ for the last digit, then set $n := \lfloor n / 10 \rfloor$.

For $n = 12345$: extract $5$, $n$ becomes $1234$. Extract $4$, $n$ becomes $123$. Extract $3$, $n$ becomes $12$. Extract $2$, $n$ becomes $1$. Extract $1$, $n$ becomes $0$. Stop.

This pattern (modulo to extract, division to remove) appears in digit manipulation problems constantly.