Let's break this down. We're going to add 1331 and 8145 together.

Step 1: We'll start by adding the digits 1 & 5 in column 1 and get 6.

Step 2: We'll start by adding the digits 3 & 4 in column 2 and get 7.

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

Step 4: We'll start by adding the digits 1 & 8 in column 4 and get 9.

So, 1331 + 8145 = 9476.

