I always try to solve problems like that just like you at first. Avoiding to use built in functions or methods. Kudos my friend.
The one problem in this case is that if you pass a really long string of numbers, the program could take a while to run trough every str(number).

It could have been much shorter.

This is some answer!

Because you do not move through the input like that.

why use while loop instead of for loop?

This would really benefit from using a for loop instad of a while loop

too long didnt read :)

thanks <3

this is painful

Using the index and length is really elegant.

string.split() already returns an array(list)....