hlut... not only does your answer provide no answer to the question, but this question has been asked (and answered) over 7 years ago.
considering the number of posts of the OP, I'm pretty certain (s)he isn't looking (here) for an answer anymore.
he creates a linked list, adds each seperate digit to it. I get that. but why having the linked list? by iterating over the digits itself he'd have found the length, no need to actually put them in a linked list.
since the part where the 'counting' could be done in this solution is about the same as what Migsoft suggested, I don't see an added solution, rather a more complicated form of the one already there.
-- but then again, I might be wrong indeed.