Q. If ABC and DEF are both 3-digit numbers such that A, B, C, D, E and F distinct and F are non-zero digits such that ABC + DEF = 1111, then what is the value of A+B+C+D+E+F?

Explanation : 

Sum of ABC and DEF

Since the sum of ABC and DEF is 1111, and all the digits are distinct and non-zero, one of the possible combinations for ABC and DEF is 785 and 326.

In the first case, the sum of the digits A+B+C+D+E+F is 7+8+5+3+2+6 = 31

So, in both cases, the sum of the digits is 31. Therefore, the correct answer is (d) 31.