OK, let's do this. We've got 3473 and 3306 and we're adding them all together.

Step 1: We'll start by adding the digits 3 & 6 in column 1 and get 9.

Step 2: We'll start by adding the digits 7 & 0 in column 2 and get 7.

Step 3: We'll start by adding the digits 4 & 3 in column 3 and get 7.

Step 4: We'll start by adding the digits 3 & 3 in column 4 and get 6.

So, 3473 + 3306 = 6779.

