What is the sum of all 3 digit positive integers that can be formed using the digits 1, 5, and 8, if the digits are allowed to repeat within a number R?
Choose the correct choice from the following answers.
A) 126  B) 1386  C) 3108  D) 308  E) 13986
As we are using digits 1,5, 8 and digits are allowed to repeat. Each of the unit, tenth and hundredth digit can be used by each of three digits.   So,Total possible numbers with these digits=3 X 3 X 3 =27.   First, As we have 27 three digit number, Sum will be for sure more than 2700..Eliminate options A,B,D   Second, If you imagine numbers R with the given digits 1,5,8. We have numbers like 888,885,855,858,851. Sum is for sure more than 4000.Eliminate option C.   You are left withanswer 13986.
<result>E</result>
What is the sum of all 3 digit positive integers that can be formed using the digits 1, 5, and 8, if the digits are allowed to repeat within a number R?