Now that we can create new digits in memory, the next step is to be able to link digits together into a number (= a linked list of digits). We’ll take an iterative approach in which we simply keep adding on digits to the current end of our list of numbers.
Since by appending a new digit the end of the list will change, the function needs to return a pointer to the new last element of the list. Please also print the (three-digit) number stored in the newly created list and next free the space reserved for all digits.