OK, let's do this. We've got 6610 and 168 and we're adding them all together.

Step 1: We'll start by adding the digits 0 & 8 in column 1 and get 8.

Step 2: We'll start by adding the digits 1 & 6 in column 2 and get 7.

Step 3: We'll start by adding the digits 6 & 1 in column 3 and get 7.

Step 4: We'll start by adding the digits 6 & 0 in column 4 and get 6.

So, 6610 + 168 = 6778.

