(a) Write a recursive procedure (digits n) that computes the number of digits in the integer n using a linear recursive process. For example, (digits 42) should return 2 and (digits 13579) should return 5.
(b) Rewrite (a) such that a linear iterative process is produced. Call the procedure digits-it.
(c) Using the substitution model, show that your procedure in (b) generates a linear iterative process.