What is the sum of the smallest and the greatest four-digit numbers that can be formed by the digits 4, 0, and 5 such that the digits are not repeated more than twice?
Smallest four digit number = 4005
Sum of the digits = 4 + 0 + 0 + 5 = 9
Greatest four digit number = 5540
Sum of the digit = 5 + 5 + 4 + 0 = 14