Let's break this down. We're going to add 6060 and 331 together.

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

Step 2: We'll start by adding the digits 6 & 3 in column 2 and get 9.

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

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

So, 6060 + 331 = 6391.

