Let's break this down. We're going to add 11 and 8502 together.

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

Step 2: We'll start by adding the digits 1 & 0 in column 2 and get 1.

Step 3: We'll start by adding the digits 0 & 5 in column 3 and get 5.

Step 4: We'll start by adding the digits 0 & 8 in column 4 and get 8.

So, 11 + 8502 = 8513.

