Answer
922
Work Step by Step
First column: 1+2+9 = 12
The 2 in the ones column is written and the 1 in the tens column is carried to the next column.
Second column: 6 + 4 + 1 + additional carried 1 from the previous column = 12
The 2 in the ones column is written and the 1 in the tens column is carried to the next column.
Third column: 8 + 0 + 0 + additional carried 1 from the previous column = 9
The 9 is written in the last column.
The digits we are left with are 9, 2 and 2, so therefore the solution to the question is 922.