We are presented with 3220 and 3315. Let's work out the sum.

Step 1: We'll start by adding the digits 0 & 5 in column 1 and get 5.

Step 2: We'll start by adding the digits 2 & 1 in column 2 and get 3.

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

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

So, 3220 + 3315 = 6535.

