What is the tens' digit Q of the sum of the first 40 terms of 1, 11, 111, 1111, 11111, 111111, ...?  Choose the correct choice.
A) Q=2  B) Q=3  C) Q=4  D) 8  E) 9
All of the first 40 terms have 1 at the units place.   Except the first term, the tens digit of all the remaining 39 terms is 1.   So now if you do the addition   1 1   1 1   . . .   . . .   . . .   1 1   0 1   3 0   Answer is Q=3
<result>B</result>
What is the tens' digit Q of the sum of the first 40 terms of 1, 11, 111, 1111, 11111, 111111, ...?