OK, let's do this. We've got 3005 and 6433 and we're adding them all together.

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

Step 2: We'll start by adding the digits 0 & 3 in column 2 and get 3.

Step 3: We'll start by adding the digits 0 & 4 in column 3 and get 4.

Step 4: We'll start by adding the digits 3 & 6 in column 4 and get 9.

So, 3005 + 6433 = 9438.

