OK, let's do this. We've got 8433 and 355 and we're adding them all together.

Step 1: We'll start by adding the digits 3 & 5 in column 1 and get 8.

Step 2: We'll start by adding the digits 3 & 5 in column 2 and get 8.

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 8 & 0 in column 4 and get 8.

So, 8433 + 355 = 8788.

