5. For any positive integer n, we define the function f n ( ) to be the sum of the
digits of n and the number of digits of n. For example, f (218) = + + + = 2 1 8 3 14 .
(Note: The first digit of n, reading from left to right, cannot be 0).
What is the sum of maximum and minimum values of n such that f n ( ) = 6 ?
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