What is the sum of all 3 digit positive integers that can be formed using the digits 1, 4, and 7, if the digits are allowed to repeat within a number?
Pick one
A) 10,655	B) 11,988	C) 12,433	D) 13,766	E) 14,322
The number of these 3-digit numbers is   3*3*3= 
<gadget id="calculator">  3*3*3</gadget>
<output>27</output>
27   Each digit 1, 4, and 7 will appear in the ones, tens, and hundreds place 9 times each.   The sum equals 9(111) + 9(444) + 9(777)= 11,988   The answer is 11,988.
<result>B</result>
What is the sum of all 3 digit positive integers that can be formed using the digits 1, 4, and 7, if the digits are allowed to repeat within a number?