Here we go! We're going to add 3331 and 6013 together.

Step 1: We'll start by adding the digits 1 & 3 in column 1 and get 4.

Step 2: We'll start by adding the digits 3 & 1 in column 2 and get 4.

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

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

So, 3331 + 6013 = 9344.

